On-page SEO: how to optimize a single page
On-page SEO covers everything on the page itself that helps it rank and serve the reader. It is the most controllable part of SEO, and getting the basics right on each important page compounds. The guiding rule is simple: write a clear, useful, well-structured page for a person first, then make sure the technical basics are tidy. This checklist covers the elements in the order worth working through them.
Start with the intent
Before touching any tag, decide what one question or need this page answers, and who is asking. A page that tries to answer several different questions ranks for none of them. Everything below follows from that decision.
The title tag
The page title is what shows as the clickable headline in search results, and it is the strongest on-page signal after the content itself.
- Lead with the main topic, naturally, not as a string of keywords.
- Keep it to about 60 characters, so it is not cut off.
- Make it specific and compelling rather than generic.
- Make it unique on every page. Duplicate titles are one of the commonest and easiest-to-fix problems.
Google sometimes rewrites titles it considers poor, so a clear, accurate one that matches the page is your best defence.
The meta description
The meta description is the short summary shown under the title. It does not directly affect ranking, but it affects whether people click, which makes it effectively a free advertisement for the page.
- Aim for roughly 120 to 160 characters.
- Summarise the page and give a reason to click: a benefit, an answer, or an offer.
- Write it for the person skimming results, and make it unique per page.
Google does not always use it, and may pick a passage from the page instead, but a good one often earns more clicks.
Headings, H1 to H6
Headings define the structure of the content, and they help skimmers, screen-reader users, and search engines alike.
- One H1 per page, which is the main title and should match the page's purpose.
- H2s for the main sections, and H3s for the points within them.
- Do not skip levels, such as going from H1 straight to H3, and do not use a heading just to get a larger font.
- Make each heading describe what follows it.
The URL
A clean URL tells people and search engines what a page is about before they click.
- Short and descriptive: /website-design, not /page?id=42.
- Lowercase, with words separated by hyphens.
- Include the relevant term naturally, and reflect the site's structure.
- Decide on clean URLs at the start. Changing them later means setting up redirects to avoid losing what the page has earned.
The content
- Answer the searcher's question fully and early, then add depth.
- Cover the related questions people ask next, and the likely objections.
- Use plain language, short paragraphs, and lists where they help.
- Show real experience: specifics, examples, and numbers you can stand behind.
- Link to related pages on your site, and from them back to this one, using descriptive link text.
Images and alt text
Images affect both speed and search visibility, and a few habits cover most of it.
- Alt text is a short description of what an image shows. It lets people using screen readers understand the image, and it helps search engines know what it depicts. Describe what the image shows simply and specifically, in a phrase rather than a paragraph, and skip "image of", because screen readers already announce that. Leave it empty for purely decorative images.
- Use descriptive filenames, such as dental-clinic-toronto.jpg rather than IMG_1234.jpg.
- Add captions where they genuinely help the reader.
- Size images correctly and use modern formats, so they load fast.
- Include important images in your sitemap if image search matters to you.
Good alt text also supports your accessibility obligations, which is a better reason to write it than ranking.
The technical basics on the page
- It loads quickly and works properly on a phone.
- It is accessible: readable contrast, usable with a keyboard, labelled forms.
- It is indexable, and the canonical points where it should.
How to prioritise
You will not optimise every page equally, nor should you. Start with the pages that earn or could earn enquiries: the homepage, your main service pages, and your location page if you have one. Fix duplicated titles, missing descriptions, and unclear headings there first, and treat the rest as a routine to apply whenever you write or update a page.