The test/dev/stage environment of the site should be non-accessible for Google: it should be blocked via robots.txt as well as require authentication to access.
Every page of the site should be shown through a single URL only (every www, HTTP, etc. URL version should 301-redirect to its non-www and HTTPS URL version.)
URL names should be descriptive, including its category, feature or product name of the page in lowercase and in the same language of the content they feature
Every category, sub-category, features, help, product, etc. page that is meant to be ranked should be indexable and feature an index, follow meta robots tag and a self-referring canonical tag, including the indexable URL
A robots.txt file should be included in the live/production site at .com/robots.txt, to disallow the crawling of the pages that are not meant to be crawled, indexed nor ranked. The meant to be indexed pages shouldn't be blocked through the site robots.txt
Every meant to be indexed page should be internally linked through the relevant site navigation, parent category/parent pages, as well as cross-linked by "related pages" covering similar topics. Non-indexable, error, redirected, or canonicalized URLs shouldn't be linked.
The internal search result pages of the site (those generated by the search functionality within the site) shouldn't be crawled nor indexed, by including a meta robots noindex, follow tag, as well as by blocking their crawling via the robots.txt, to avoid content duplication/cannibalizaton issues with the Website indexable pages.
Every page of the site should be responsive and pass Google's mobile validation: https://search.google.com/test/mobile-friendly
Every indexed page should be included in the site XML Sitemap (avoiding to include non-indexable, error, redirected, or canonicalized pages)
Pages should have a lower 2.5 seconds in LCP, less than 100ms in FID, and less than 0.1 of CLS - to be tested using the PageSpeed insights tool https://developers.google.com/speed/pagespeed/insights/?hl=en
Pages should feature the relevant Schema.org structured data defined for it: FAQs, How-Tos, VideoObject, Article, etc. The structured data shouldn't generate Schema.org markup errors and pass the validation of https://search.google.com/test/rich-results
Every page that is shown in more than one country/language version of the site should feature hreflang annotations to specify its own language/country targeting as well as the one of their alternate URLs versions
Every page should feature a unique descriptive title tag, including the targeted query for which it needs to rank for, that should be included at the start.
Every page should feature a unique descriptive meta description, including the targeted query for which it needs to rank for, giving context about the value to be obtained from the page.
Every page should feature a unique descriptive H1 heading tag, including the page specific category, feature, content, product information
Every page should feature unique, relevant and comprehensive text information about the feature, product or steps that are offered in it that is indexable, and shown by default to the user, without hiding it in tabs.
If a page URL needs to be changed then the page should 1) include the new URL in the canonical tag, 2) the old URL should be 301-redirected to the new URL version, 3) links going to the old page should be updated and 4) the XML sitemap should be updated with the new URL, removing the old one.
When any page of the site is removed, because its information is not offered anymore, then instead of showing a 404 http status it should 301 redirect to its new/most similar version, or parent/category page -the one that is more relevant, specific-. All internal links that used to go to that about to disappear page should be eliminated, as well as the old page inclusion in the XML sitemap.