Master Secondary Keywords to Leapfrog Your SEO Competitors

When setting up your webpage for Search Engine Optimisation (SEO), keywords are extremely important. Primary and secondary keywords help direct traffic from search engines to your site when a specific keyword is searched.

Your choice of keywords will determine the overall effectiveness of your SEO. When optimising your site for SEO, part of the process is choosing one primary keyword or phrase and several supporting secondary keywords.

The challenge is matching your targets to the actual search volume of different queries while ensuring your content covers the topic comprehensively enough to rank.

This is where the strategic use of primary and secondary keywords makes the difference between appearing on page 8 of Google and breaking into the top 10 results.

The Difference Between Secondary and Primary Keywords

Both primary and secondary keywords serve as the foundation of any effective SEO strategy. One doesn’t function well without the other, and they complement each other when properly implemented.

However, they differ in several important respects. Having a clear understanding of which keywords are your primary targets and which serve as secondary support will inform the exact content structure you create and how you optimise each page.

Primary Keywords

The main difference between secondary and primary keywords is that, for SEO, you usually have one primary keyword per page, with multiple secondary keywords supporting it.

To understand the purpose of secondary keywords, you must first understand the role of primary keywords within your overall keyword strategy.

The purpose of primary keywords is to match potential customers with your site based on their search terms. They are considered the backbone of any SEO strategy, and their proper use leads to measurable results.

The primary keyword should appear throughout a piece of content, including the page title, the H1 heading, the URL slug, and, naturally, the body copy. If it’s an article, it should appear in the first paragraph and be reinforced several times throughout the content.

That way, the keyword used to describe the page accurately reflects its essential purpose and primary topic.

Example from ProfileTree’s work: When we built a website for a Belfast solicitor, the homepage targeted “solicitors Belfast” as the primary keyword. Every service page then had its own distinct primary keyword: “family law Belfast,” “conveyancing Northern Ireland,” “employment law advice Ulster.” Each page focused on one clear entity.

Secondary Keywords

Secondary keywords serve the same purpose as the primary ones: supporting them. The days of simply stuffing primary keywords into an article are gone. Search engines are now more concerned with topics than individual keyword phrases.

For this reason, it’s important to include secondary keywords that are semantic variations of your primary target. These are keywords which express the same ideas in different words or which cover related subtopics that help search engines understand the full scope of your content.

It’s also important to include overlapping keywords to signpost the relevance of your content to the broader topic.

Finally, secondary keywords often take the form of long-tail keywords. These are phrases of three or more words which typically have lower search volumes because they’re more specific than shorter queries.

Long-tail secondary keywords are an excellent way to structure your H2 and H3 subheadings. This approach is particularly effective for appearing in featured snippets on search results pages, as Google often pulls direct answers from well-structured subheadings that match specific user queries.

How ProfileTree applies this: For that same Belfast solicitor, the “family law Belfast” service page used secondary keywords like “divorce solicitors Northern Ireland,” “child custody advice Belfast,” “separation agreements Ulster,” and “family mediation services.” These terms all support the primary focus while capturing different ways potential clients search for these services.

Tertiary Keywords

While most SEO discussions focus on primary and secondary keywords, there’s a third tier worth understanding: tertiary keywords.

Tertiary keywords are broader industry terms or tangentially related topics that build topical authority without being your direct focus. They’re terms you might mention in passing or cover briefly to demonstrate comprehensive knowledge of your field.

Example: For a page targeting “SEO Belfast” (primary) with secondary keywords like “search engine optimisation Northern Ireland” and “Google rankings Belfast,” tertiary keywords might include “digital marketing,” “web analytics,” “conversion rate,” or “content strategy.” These terms naturally arise when explaining SEO, but they aren’t the page’s focus.

When ProfileTree uses tertiary keywords: In our content marketing for a Derry hotel client, tertiary keywords helped build topical authority. The primary keyword was “hotels Derry,” secondary keywords included “accommodation Londonderry” and “city centre hotels Northern Ireland,” while tertiary keywords like “Causeway Coast tourism,” “Walled City attractions,” and “conference venues Ulster” appeared naturally throughout the content, connecting the hotel to the broader tourism ecosystem without diluting the main focus.

How to Use Secondary Keywords

For search engines like Google, pages rank higher when they focus on a single, clear topic with comprehensive coverage. Your keywords should reflect that precision.

When setting primary keywords, the most important advice is to stay focused and avoid being too general. The aim of primary and secondary keywords is to attract a specific target audience, so your selection needs to reflect that intent.

Otherwise, you’ll be directing unfocused traffic to the site. However, don’t make the opposite mistake. If your keywords are too specific or niche, they’ll have virtually no search volume.

The advantage of secondary keywords is the flexibility they provide. Unlike primary keywords, where you typically select just one per page, with secondary keywords, you can employ 4-8 terms that capture different angles of the same topic.

Use Secondary Keywords for Social and PPC

Use secondary keywords across all your online marketing efforts, not just on-page SEO.

Your content channels may differ, but the goal remains the same. You want to maximise your business’s visibility and drive qualified traffic to your website. Don’t forget to incorporate your primary and secondary keywords in every social media post linking to your website, in display ad copy, and in paid search campaigns.

ProfileTree’s approach: When we run digital marketing campaigns for Northern Ireland businesses, we test different keyword variations in Google Ads and social media posts. The data from these campaigns often reveals which secondary keywords have the strongest commercial intent, informing our organic SEO strategy.

Secondary Keyword Density

The recommended number of secondary keywords to target per page ranges from 4-8, depending on the content length and topic complexity.

You can include more than 8 if the content genuinely requires it, but avoid going above 10. Adding too many secondary keywords dilutes focus and diminishes results.

Real example from ProfileTree’s SEO work: For a 2,500-word guide on “WordPress web design Belfast,” we targeted:

• Primary: “WordPress web design Belfast”
• Secondary (6 terms): “WordPress development Northern Ireland,” “custom WordPress sites,” “WordPress SEO setup,” “WordPress maintenance Belfast,” “WordPress security,” “responsive WordPress design”
• Each secondary keyword informed a major section of the article with its own H2 heading

Focus on Topics, Not Just Keywords

When listing secondary keywords, it’s easy to get sidetracked and lose focus on the core topic. Set your mindset to someone searching for your page and list the search terms they would realistically use to find exactly what you offer.

Your secondary keywords should be more specific variations of your primary topic rather than branching into unrelated areas. When you feel you’re beginning to stray from the main topic, you’ve likely identified the boundary of useful secondary keywords.

What ProfileTree avoids: If a page targets “video production Belfast,” we don’t add “web design” or “SEO services” as secondary keywords even though we offer those services. Instead, secondary keywords stay within the video production topic: “corporate video Northern Ireland,” “animation services Belfast,” “YouTube video production,” “product video filming,” “explainer videos Ulster.”

Find Long-Tail Keywords

Keywords aren’t exclusively single words—they can be phrases or short sentences. This applies to both primary and secondary keywords.

A thesaurus is helpful when researching secondary keywords because different searchers use different terminology. For example, if one secondary keyword is “advantages of local SEO,” you might also target “benefits of local search optimisation” or “value of appearing in Google Maps.”

ProfileTree’s keyword research process: When we audit existing content for Northern Ireland clients, we use Google Search Console to identify long-tail queries already driving impressions. Often, pages rank on pages 3-5 for valuable long-tail secondary keywords with minimal optimisation. Adding dedicated sections targeting those terms can move the page to page 1.

Balance Primary and Secondary Keywords

Primary and secondary keywords work together, and it’s essential to use this relationship strategically.

If you’ve chosen a primary keyword, branch out to more specific variations or related subtopics. For example, if your primary keyword is “SEO training,” your secondary keywords might include “SEO workshop Belfast,” “search optimisation course,” “Google ranking training,” and “SEO fundamentals for beginners.”

Build outward from your primary topic, maintaining clear relevance throughout.

How we structure ProfileTree’s service pages: Our main SEO page targets “SEO Belfast” as primary. Supporting pages target secondary variations: “local SEO Northern Ireland,” “technical SEO services,” “SEO audits Belfast,” “Google Business Profile optimisation.” Each page has its own URL and focus, but internal links connect them into a cohesive topic cluster.

Focus on Providing Value for Readers

While good SEO directs traffic to your site, making your content genuinely useful and engaging improves user behaviour signals and strengthens your rankings over time.

Whether creating content or working through the SEO process, always keep your audience in mind. You need to understand what they’re looking for and how they’ll search for it. This keeps your strategy focused and ensures you’re targeting keywords that match real commercial intent, not just search volume.

What ProfileTree has learned: After building over 1,000 websites since 2011, we’ve found that pages answering specific questions outperform generic “overview” content. When we added FAQ sections that answered actual client questions to our service pages, organic traffic increased by 40% within 6 months. Secondary keywords informed which questions to answer.

Secondary Keyword Research Tools

At this point, you might be wondering how to generate so many effective keywords efficiently. If you’re not an SEO professional, keyword research might seem overwhelming, but it’s achievable with the right tools.

Keyword generators are online tools that expand your primary keyword into multiple secondary keyword suggestions using data gathered from search engines, competitor analysis, and search trends.

By analysing search patterns and currently popular keywords, these tools help you build an effective keyword list for your SEO strategy. However, never rely entirely on automated suggestions—you must review the generated secondary keywords carefully and decide for yourself whether they’ll be genuinely useful for your specific audience and business goals.

Google Keyword Planner Tool

Keyword Planner generates a comprehensive list of keyword suggestions based on the primary keywords you input. With a Google Ads account (free to create), you can view monthly search volume, competition level, and suggested bid amounts for all keywords.

The search volume data is UK-specific when you select the United Kingdom as your target location, making it particularly valuable for Belfast and Northern Ireland businesses targeting local markets.

How ProfileTree uses Google Keyword Planner: Before building content strategies for SME clients, we run their core service terms through Keyword Planner, filtered for “United Kingdom” to identify secondary keywords with realistic search volume. We ignore suggestions with zero volume unless they answer specific client questions, and we filter out terms with search intent that don’t match the page’s purpose (informational vs transactional).

Ahrefs Keywords Explorer

Ahrefs provides detailed keyword data, including search volume, keyword difficulty scores, click-through rate estimates, and related keyword suggestions. The tool shows which keywords competitors rank for and identifies content gaps.

While Ahrefs is a paid tool, it offers more granular data than free alternatives, particularly for analysing competitor keyword strategies and finding long-tail secondary keyword opportunities.

ProfileTree’s experience: Ahrefs’ “Questions” feature is particularly useful for finding secondary keywords phrased as questions. These often become H2 or H3 subheadings that can capture featured snippets. For a legal client, we discovered “how much does conveyancing cost in Northern Ireland” had decent volume with low competition—it became a dedicated FAQ section that now ranks in position 3.

AnswerThePublic

AnswerThePublic visualises search questions and phrases based on your primary keyword input. It organises results by question type (what, why, how, where, when), prepositions (for, to, with, without), and comparisons.

While many suggested keywords may not be relevant, the tool excels at uncovering question-based secondary keywords that match actual user search behaviour.

When ProfileTree uses AnswerThePublic: It helps identify the questions our target audience is genuinely asking during content planning for blog articles and in-depth guides. These questions become section headings, ensuring our content provides comprehensive coverage that search engines reward. It’s particularly effective for topics where we have deep expertise but need to understand how non-experts phrase their queries.

Semrush Keyword Magic Tool

Semrush’s Keyword Magic Tool generates extensive keyword lists with filtering options by search volume, keyword difficulty, search intent, and question-based queries.

The tool also identifies related keywords and semantic variations, making it valuable for building comprehensive secondary keyword lists that cover all angles of a topic.

Free Alternative: Google Search Suggestions

Don’t overlook Google’s own suggestion features, which are completely free:

• Autocomplete suggestions: Start typing your primary keyword into Google and note the autocomplete suggestions that appear
• “People also ask” boxes: These questions represent real user queries related to your topic
• “Related searches” at the bottom of search results pages show semantic variations and related queries

ProfileTree’s quick keyword research method: For smaller projects or blog posts, we often start with these free Google features before moving to paid tools. Type the primary keyword, note autocomplete suggestions, scroll to the related searches, expand several “People also ask” questions, and note those suggestions too. In 10 minutes, you’ll have 20-30 potential secondary keywords to evaluate.

Where to Place Secondary Keywords for Maximum Impact

Once you’ve researched and selected your secondary keywords, strategic placement determines how effectively they support your SEO.

H2 and H3 Subheadings

Your most important secondary keywords should appear in H2 subheadings, which carry significant SEO weight and help search engines understand your content structure.

Use H3 subheadings for more specific secondary keyword variations or long-tail phrases that support your H2 sections.

Structural example from ProfileTree’s content:

H1:Web Design Belfast: Professional Websites for Northern Ireland Businesses

• H2: WordPress Web Design Belfast (secondary keyword 1)
  • H3: Custom WordPress Themes for NI Businesses
  • H3: WordPress SEO Optimisation
• H2: E-commerce Website Development (secondary keyword 2)
  • H3: Shopify Store Setup
  • H3: WooCommerce Solutions
• H2: Responsive Web Design Services (secondary keyword 3)

Body Content and Natural Context

Integrate secondary keywords naturally throughout your body content, focusing on context and readability rather than arbitrary keyword density targets.

Modern search algorithms understand semantic relationships, so using synonyms and natural language variations is more effective than repetitively using exact keyword phrases.

ProfileTree’s writing approach: We write content first for human readers, then review to ensure secondary keywords appear naturally. If a secondary keyword doesn’t fit naturally into a paragraph, we don’t force it—instead, we consider whether that keyword actually belongs on this page or whether it signals a need for a different page entirely.

Image Alt Text and Meta Descriptions

Include relevant secondary keywords in image alt text where they genuinely describe the image content. This serves both SEO and accessibility purposes.

Use secondary keyword variations in your meta description to increase the likelihood of your snippet matching varied user search queries, potentially improving click-through rates.

Example: For a page about “SEO services Belfast” with secondary keywords including “search engine optimisation Northern Ireland” and “Google ranking services”:

Meta description: “ProfileTree provides SEO services in Belfast and across Northern Ireland. Our search engine optimisation strategies help businesses improve Google rankings and attract local customers. Free consultation available.”

The meta description naturally incorporates secondary keywords while remaining readable and compelling.

Internal Linking Anchor Text

Use secondary keywords as anchor text when linking internally between related pages on your website. This reinforces the topical relationship between pages and distributes link equity while signalling to search engines what the linked page is about.

ProfileTree’s internal linking strategy: Our SEO service page links to our web design service using anchor text like “SEO-optimised web design” rather than “click here” or generic phrases. This reinforces the relationship between services while naturally incorporating secondary keywords.

Common Mistakes to Avoid

Even with the right secondary keywords identified, poor implementation undermines your SEO efforts. These are the most frequent mistakes we see when auditing websites for Belfast and Northern Ireland clients, and how to avoid them.

Keyword Stuffing

Forcing secondary keywords into content where they don’t fit naturally harms readability and can trigger search engine penalties.

If you’re using a secondary keyword more than 2-3 times in a 500-word section, you’re likely overstuffing. Focus on comprehensive topic coverage using natural language instead.

What ProfileTree avoids: We’ve audited competitor websites where every paragraph contains the same keyword phrase repeated awkwardly. This outdated approach doesn’t work. Search engines are sophisticated enough to understand topic coverage without seeing the exact phrase every 50 words.

Drifting from Search Intent

Not all keywords with similar wording serve the same search intent. Mixing informational and transactional secondary keywords on the same page confuses search engines about the page’s purpose.

Example of intent mismatch: A page targeting “SEO services Belfast” (transactional intent) shouldn’t use “what is SEO” or “how does SEO work” as secondary keywords (informational intent). Those questions belong in a separate educational article.

Using Competitors’ Brand Names as Keywords

Never target competitor brand names or trademarked terms as secondary keywords unless you’re writing a genuine comparison or review. This wastes effort on keywords you can’t realistically rank for and may create legal issues.

ProfileTree’s approach for international clients: When we build sites for Northern Ireland businesses that also serve UK and international markets, we use UK spellings as the primary terms but ensure US variations appear in the content where natural. This captures both audiences without appearing to have spelling errors to either group.

Ignoring Search Volume Reality

Targeting secondary keywords with zero search volume (unless they answer specific client questions) or focusing only on high-volume terms with overwhelming competition both represent strategic mistakes.

The most effective secondary keywords typically have moderate search volume (50-500 searches per month for local markets) with achievable competition levels.

Secondary Keywords in International SEO

For businesses operating across multiple English-speaking markets, spelling variations serve as natural secondary keywords that require minimal additional optimisation.

A page optimised for UK audiences using “optimisation” will still rank for US searches using “optimisation” without explicit targeting. However, if you’re specifically targeting both markets and naturally include both variations throughout your content, it improves performance in both regions.

ProfileTree’s experience with international clients: For a technology client selling software in both the UK and US markets, we created location-specific landing pages. The UK page used “colour schemes” and “optimisation”, while the US page used “colour schemes” and “optimisation.” Both pages ranked well in their target markets because they aligned with local language expectations.

For Northern Ireland businesses, this matters because your market spans:

• Local Northern Ireland searches (often using UK spellings)
• Republic of Ireland searches (UK spellings)
• UK-wide searches (UK spellings)
• Potential international traffic (mixed spellings)

Using UK spellings as primary, with occasional US variants appearing naturally, captures the broadest audience.

Secondary Keywords for Local SEO

Local businesses need location-specific secondary keywords in addition to service-based terms.

For Belfast businesses, effective secondary keywords might include neighbourhood names, regional variations, and broader geographic terms:

Example: A Belfast restaurant’s keyword strategy:

• Primary: “restaurants Belfast city centre”
• Secondary: “Cathedral Quarter dining,” “fine dining Belfast,” “Northern Ireland restaurants,” “best restaurants Ulster,” “Belfast food scene”
• Tertiary: “Titanic Quarter,” “Belfast nightlife,” “Northern Irish cuisine”

ProfileTree’s local SEO approach: When we optimise Google Business Profiles for Belfast clients, we ensure the services listed in GBP use the same terminology as the H1 headings on the corresponding website service pages. This consistency reinforces location-service relationships for local pack rankings.

For a Derry-based hotel:

• Primary: “Hotels Derry”
• Secondary: “Londonderry accommodation,” “city centre hotels,” “Walled City lodging,” “Northern Ireland hotels,” “Causeway Coast hotels”

Each secondary keyword captures a different search pattern while maintaining geographic relevance.

Conclusion

Secondary keywords help your pages rank for multiple related queries instead of just one exact phrase. When properly researched and placed in headings, body content, and metadata, they capture the different ways your audience searches while giving search engines full context about your topic.

ProfileTree has implemented secondary keyword strategies for over 1,000 projects across Belfast, Northern Ireland and the UK since 2011. The most successful approach combines thorough keyword research, strategic placement, and ongoing refinement based on actual performance data.

FAQs

Need help developing a keyword strategy for your business? ProfileTree’s SEO services combine technical expertise with a practical understanding of local markets. Get in touch to discuss improving your search visibility.