DIY Technical and On-Page SEO Audit: A Step-by-Step Walkthrough

A technical and on-page audit finds the problems that quietly hold a site back: pages search engines cannot find, duplicate titles competing with each other, slow templates, broken links and redirect chains, and content that does not clearly signal what it is about. Most of these are fixable without a developer — and fixing them is often the fastest SEO win a site will ever get.

This walkthrough takes you from crawlability through on-page optimisation in a logical order, with what to check, which free tools to use and how to fix the common problems. Work through it once thoroughly, then revisit the key checks quarterly.

A Full DIY SEO Audit Walkthrough, Start to Finish

The audit follows how search engines process a site:

1. Crawlability and indexing — can search engines find and index your pages?
2. Site health — HTTPS, mobile, speed, URL structure, redirects and broken links.
3. Duplication — duplicate content, titles and descriptions.
4. On-page — titles, descriptions, headings, keyword placement, images and internal links.
5. Content quality — depth, readability and formatting.
6. Special situations — migrations, custom-built sites and subdomain blogs.

Tools you need (all free): Google Search Console, Bing Webmaster Tools, PageSpeed Insights, a crawler (the free tier of Screaming Frog covers 500 URLs), and a spreadsheet to log findings by priority.

DIY Technical SEO: What a Beginner Can Realistically Fix

Most technical issues on small sites are configuration, not code: a noindex left on after launch, a missing sitemap, broken internal links, oversized images, missing titles, redirect chains. Those are all fixable through your CMS, plugins or hosting panel. Hand off to a developer when problems involve server configuration, JavaScript rendering, complex site architecture or custom code you do not understand.

Step 1: Crawlability and Indexing

Checking Whether Your Site Is Actually Indexed, Yourself

Start in Search Console's Pages report (Indexing → Pages). It shows how many pages are indexed and why others are not — "Crawled – currently not indexed", "Excluded by 'noindex' tag", "Duplicate without user-selected canonical" and so on. For a specific URL, use the URL Inspection tool. A quick site:yourdomain.com search gives a rough picture, but Search Console is the authoritative source.

Common culprits: a site-wide "discourage search engines" setting left on from development, noindex tags on templates, canonical tags pointing at the wrong page, or pages with so little unique content that Google chooses not to index them.

DIY Robots.txt Basics for Non-Developers

robots.txt (at yourdomain.com/robots.txt) tells crawlers which areas they should not crawl. Key points:

• Disallow: / blocks the entire site — a classic launch-day disaster.
• Blocking a page in robots.txt does not remove it from search results; use a noindex tag for that (and keep the page crawlable so the tag can be seen).
• Do not block CSS or JavaScript files that pages need to render.
• Use Search Console's robots.txt report to check for errors.

A typical small site needs only a few lines — allow everything, block admin areas, and reference the sitemap.

Sitemap Reference in Robots.txt

Add a line pointing to your XML sitemap — Sitemap: https://yourdomain.com/sitemap.xml — anywhere in robots.txt. It helps every search engine discover the sitemap, not just those where you submitted it manually. You can list several sitemap lines if you have more than one.

DIY Sitemap Creation and Submission

An XML sitemap lists the URLs you want indexed. Most CMSs and SEO plugins generate one automatically. Make sure it includes only canonical, indexable pages that return a 200 status (no redirects, noindex pages or 404s), then submit it in Search Console and Bing Webmaster Tools. Check the sitemap report periodically for errors and for a big gap between "submitted" and "indexed".

Step 2: Site Health

DIY HTTPS and Basic Security Checklist

• The whole site loads on HTTPS with a valid certificate (free certificates are standard with most hosts).
• HTTP and www/non-www variants redirect to one canonical version.
• No mixed-content warnings (images or scripts loaded over HTTP).
• CMS, themes and plugins are up to date; unused ones are removed.
• Admin accounts use strong passwords and two-factor authentication.
• Search Console's Security issues report is clean.

DIY Mobile-Friendliness Check

Google indexes the mobile version of your site, so mobile is the version that counts. Check key templates on a real phone: readable text without zooming, tap targets that are not cramped, no horizontal scrolling, and no intrusive pop-ups covering content. Make sure the mobile version contains the same content and structured data as desktop. Lighthouse in Chrome DevTools reports mobile issues for any page.

DIY Site Speed Troubleshooting Without Hiring a Developer

Run your main templates (home, a category, an article, a product) through PageSpeed Insights and focus on the Core Web Vitals: Largest Contentful Paint (loading), Interaction to Next Paint (responsiveness) and Cumulative Layout Shift (visual stability). The usual fixes you can make yourself:

1. Compress and resize images; serve modern formats like WebP; lazy-load images below the fold.
2. Enable caching (a caching plugin or your host's built-in cache).
3. Remove unused plugins, apps and third-party scripts — chat widgets, trackers and embeds are frequent offenders.
4. Use a CDN.
5. Set explicit width and height on images and embeds to stop layout shifts.
6. Upgrade from cheap overloaded hosting if the server response time is consistently slow.

DIY URL Structure Review

Good URLs are short, readable and descriptive: /blog/compost-smells-bad/ rather than /index.php?p=8213. Use lowercase and hyphens, avoid unnecessary dates and parameters, and keep a logical hierarchy. Do not change existing URLs just to make them prettier — every change needs a redirect and risks losing signals. Fix structure going forward, and only migrate old URLs when the benefit is clear.

Subdomains vs Subdirectories

A subdirectory (example.com/blog/) is part of your main site; a subdomain (blog.example.com) can be treated more like a separate site. For most businesses, putting the blog, help center and other content in subdirectories keeps everything under one domain's authority and is simpler to manage. Use subdomains when there is a genuine technical or organisational reason — a separate platform, a distinct product or a different country team.

DIY Redirect Cleanup After a Site Change

Crawl your site and check for:

• Redirect chains (A → B → C): update them so A redirects straight to C, and update internal links to point to the final URL.
• Redirect loops: fix immediately; they make pages unreachable.
• Temporary (302) redirects used for permanent moves: change to 301.
• Old URLs returning 404 that should redirect to a relevant replacement.

Fixing Broken Links Yourself

Your crawler lists internal links that return 404 errors. Update each link to the correct URL, or redirect the missing page to its closest replacement if it has backlinks or traffic. For broken outbound links, update them to a working source or remove them. Search Console's Pages report also shows 404s Google has found, including from external links.

Step 3: Duplication

Spotting Duplicate Content Yourself

Common sources of duplicate content on small sites:

• HTTP/HTTPS or www/non-www versions both accessible
• URL parameters (sorting, tracking, filters) creating copies of the same page
• Tag and category archives repeating the same posts
• Printer-friendly or AMP versions
• Product descriptions copied from manufacturers

Fix with redirects to a single version, canonical tags pointing to the preferred URL, noindex on thin archive pages, and original descriptions. Search for a distinctive sentence in quotes to find copies of your content elsewhere on the web.

DIY Duplicate Title and Meta Cleanup Across a Larger Site

Crawl the site and sort by title tag and meta description to find duplicates and blanks. Templates are often the cause — every product in a category sharing one title, or paginated pages repeating the first page's title. Fix templates first (adding product names, page numbers or categories dynamically), then hand-write titles for your most important pages.

Step 4: On-Page Optimisation

DIY Title Tag Writing for Every Page on Your Site

The title tag is your headline in search results and the strongest on-page relevance signal. A formula that works for most pages: primary keyword + specific benefit or detail + brand (if it fits), within roughly 60 characters. Examples:

• Product: "Cast Iron Skillet 12-Inch, Pre-Seasoned | BrandName"
• Article: "Why Does Compost Smell Bad? 7 Causes and Fixes"
• Service: "Emergency Plumber in Leeds — 24/7, Fixed Prices"

Every page needs a unique title that matches the page's intent.

DIY Meta Description Writing

Meta descriptions do not directly affect rankings, but they shape whether people click. Write about 150–160 characters that summarise what the page offers and why it is worth clicking, include the main keyword naturally (search engines bold matching words), and add a reason to act. Google sometimes rewrites descriptions when it finds a better match on the page; well-written, specific descriptions are rewritten less often.

DIY Header Tag Cleanup

Each page should have one H1 describing its main topic, with H2s for main sections and H3s for subsections beneath them. Common problems: multiple H1s from theme templates, headings used for styling rather than structure, skipped levels, and headings that say nothing ("More info"). Clear, descriptive headings help readers scan and help search engines understand page structure.

DIY On-Page Keyword Placement

Place the primary keyword where it naturally belongs: the title tag, the H1, the opening paragraph, at least one subheading, and the URL. Then forget the keyword and cover the topic thoroughly — related terms will appear naturally. If a sentence reads awkwardly because of a keyword, rewrite it. See using related keywords on the page.

DIY Image Optimization

• Resize images to the size they are displayed at and compress them.
• Use modern formats (WebP or AVIF) where supported.
• Give files descriptive names (cast-iron-skillet-12-inch.jpg, not IMG_0042.jpg).
• Write alt text that describes the image for people using screen readers.
• Lazy-load images below the fold, but not the main image at the top of the page.

DIY Internal Linking Audit

Internal links help search engines discover pages and understand which ones matter most. In your crawler, check:

• Orphan pages with no internal links pointing to them — link to them from relevant pages.
• Important pages buried many clicks from the homepage — link to them from your navigation or hub pages.
• Generic anchor text ("click here") — replace with descriptive text.
• Broken internal links — fix them.

A simple habit: every time you publish, add links from two or three existing related pages to the new one.

Step 5: Content Quality

DIY Blog Post Optimization Checklist

• [ ] Clear search intent and primary keyword chosen
• [ ] Title tag and H1 include the main topic
• [ ] Answer or key point appears early
• [ ] Descriptive H2/H3 structure covering sub-questions
• [ ] Original insight, examples or experience
• [ ] Internal links to and from related pages
• [ ] Images compressed with alt text
• [ ] Meta description written
• [ ] Facts and dates up to date

DIY Readability and Formatting Pass

Online readers scan. Use short paragraphs, descriptive subheadings, bullet points and tables where they help, and bold key takeaways sparingly. Read the page aloud: where you stumble, rewrite. Put the most important information first. Readable content keeps people on the page — and satisfied readers are what search engines are trying to find.

DIY Content Length and Depth Check

There is no ideal word count. Compare your page to the top results: do they answer questions yours does not? Do they include examples, data or steps you skipped? Depth means answering the query completely and helpfully — sometimes in 300 words, sometimes in 3,000. Expand pages that are thinner than the results they compete with; trim padding that adds length but not value.

Step 6: Special Situations

DIY SEO When Migrating Platforms

Migrations are the most common cause of sudden traffic losses. Before switching platforms:

1. Crawl and export every current URL, title and meta description.
2. Record current traffic and rankings as a baseline.
3. Map every old URL to its new URL and implement 301 redirects.
4. Carry over titles, descriptions, headings, structured data and internal links.
5. Test on a staging site, then launch at a quiet time.
6. After launch, crawl again, submit the new sitemap and watch Search Console daily for a few weeks.

DIY SEO for a Custom-Built Website

Custom sites lack the SEO defaults CMSs provide, so confirm the basics exist: editable titles and meta descriptions per page, one H1 per page, clean URLs, an auto-updating XML sitemap, canonical tags, correct status codes (real 404s, 301 redirects), and content that appears in the HTML rather than only after heavy JavaScript loads. Use URL Inspection's "View crawled page" to see what Google actually receives.

DIY SEO for a Blog Hosted on a Subdomain

If your blog lives on a subdomain (often because it runs on a different platform), link prominently between the blog and the main site, keep branding and navigation consistent, add both properties to Search Console, and interlink blog posts to relevant product or service pages. If it becomes practical, moving the blog into a subdirectory with proper redirects usually consolidates your SEO.

Prioritising Your Fixes

Sort findings into three groups:

The Bottom Line

A DIY audit is mostly careful checking and steady fixing. Make sure search engines can find and index your pages, keep the site fast, secure and free of broken links and duplicates, then make every important page's topic unmistakable through titles, headings and internal links. Re-run the critical checks quarterly and after any major site change.

Next step: Run a quick health check with the free SEO Audit tool, then work through the priority table above.