On-Page SEO: The Complete Optimisation Checklist for 2025

What Is On-Page SEO?

On-page SEO refers to all the optimisations you make on your web pages to improve their visibility in search engines. Unlike off-page SEO (which is about external signals like backlinks), on-page SEO is entirely in your control.

The Complete On-Page SEO Checklist

1. Title Tag

The title tag is the most important on-page ranking factor. Best practices:

  • Include your primary keyword, ideally near the beginning
  • Keep it under 60 characters to avoid truncation in SERPs
  • Make it compelling enough to earn clicks β€” CTR matters
  • Include your brand name at the end for recognition
  • Make every title tag unique β€” no duplicate titles

2. Meta Description

Meta descriptions don’t directly affect rankings, but they significantly influence click-through rates. Write them as ad copy:

  • Include your primary keyword (Google bolds it in results)
  • Include a clear value proposition or CTA
  • Keep under 155 characters
  • Make each one unique

3. Heading Structure (H1–H6)

  • One H1 per page, containing your primary keyword
  • H2s for major sections, using secondary keywords where natural
  • H3s for subsections within H2 sections
  • Use headings for structure, not keyword stuffing

4. URL Structure

  • Short, descriptive URLs (your-keyword not page-id-12345)
  • Use hyphens not underscores
  • Include the primary keyword in the URL
  • Avoid unnecessary parameters

5. Content Quality and Depth

Google rewards content that comprehensively satisfies search intent. Ask:

  • Does this answer the user’s question fully?
  • Does it cover related subtopics they might also need?
  • Is it more useful than what currently ranks for this query?
  • Is it written for humans first, not search engines?

6. Keyword Usage

  • Include your primary keyword in the title, H1, first paragraph and throughout the content naturally
  • Use semantic variants and related terms (LSI keywords)
  • Avoid keyword stuffing β€” it reads badly and can trigger penalties

7. Image Optimisation

  • Descriptive file names (london-seo-agency.jpg not IMG_1234.jpg)
  • Alt text describing the image with keywords where natural
  • Compress images (use WebP format)
  • Specify width and height to prevent CLS

8. Internal Links

  • Link to related pages on your site with descriptive anchor text
  • Ensure no important pages are more than 3 clicks from the homepage
  • Build a logical hierarchy that passes authority to your key pages

9. Schema Markup

Add appropriate structured data: Article for blog posts, FAQPage for pages with Q&A, Service for service pages, LocalBusiness for location pages.

10. Page Experience Signals

  • Core Web Vitals scores (LCP, INP, CLS)
  • Mobile friendliness
  • HTTPS
  • No intrusive interstitials