Every technical SEO checklist you can download has the same problem: it lists ninety items with no indication of which three matter. So teams work top to bottom, spend a fortnight on image alt text, and never reach the redirect chains that were actually costing them rankings.
This is the order I work in on client sites, most valuable first.
1. Indexation, before anything else
A page that is not indexed cannot rank, and no amount of content work changes that. Open the Pages report in Search Console and read the excluded reasons honestly. Discovered but not crawled at scale usually means a quality or crawl-budget signal. Crawled but not indexed usually means the page is thin or duplicative. Both are content problems wearing a technical costume.
2. Redirect chains and broken internal links
Every hop loses a little and wastes crawl. Chains accumulate quietly through redesigns and URL tidying until a link passes through four hops to reach a page. Crawl the site, flatten every chain to one hop, and fix internal links that point at redirects rather than destinations.
3. One page per keyword
Cannibalisation is a technical problem in practice even though it looks editorial. Run a query-to-page report from Search Console and find terms where the ranking URL keeps switching. That flicker is Google telling you it cannot decide which of your pages to trust. Consolidate.
4. Core Web Vitals on mobile, in field data
Lab scores are a diagnostic, not a target. Use the field data in Search Console, work on the template with the most traffic, and fix causes rather than symptoms: oversized hero images, render-blocking third-party scripts, fonts that shift layout on load.
5. Structured data that matches the page
Organisation and site-level schema, then page-appropriate types: Article, Service, FAQPage, Product, LocalBusiness. Validate it. Schema that describes something the page does not contain is worse than none.
What can wait
Perfect alt text on decorative images. Compressing a stylesheet by four kilobytes. Chasing a lab score from 92 to 96. These are real improvements with negligible commercial effect, and they are where technical SEO time most often disappears. Fix the first five properly and most sites see movement before the list is finished. If you would rather have this done as a prioritised audit against your own data, that is what a technical SEO engagement produces.