Among the most important tests that should be done first is bloating indexing, which requires making sure that your category nd tag pages are not indexed. The other important test includes getting rid of the issue of bots trap via useless links or rendering issues as well as INP latency problems. Even if you have all the necessary content on your website, it won't pass if there are any other issues.
Preventing any form of crawling leakage should be first on your list, as such issues are merely symptom rather than causes. The causes of the problem could include errors such as 404s and redirects, which affect googlebots ability to reach a certain page. Link equity needs to flow effortlessly throughout the website as well, and core page must be reachable in no more than three clicks from the homepage.
I check for broken links and the sitemap so I can make sure my websites are crawled.