The plumbing: robots.txt, canonicals, hreflang, sitemaps, redirects and response headers.
Generate a correct robots.txt with crawl rules and sitemap.
Generate hreflang tags for multi-language / multi-region pages.
Create canonical link tags to prevent duplicate-content issues.
Build meta robots directives (index/follow, max-snippet…).
Generate an XML sitemap from your list of URLs.
Build .htaccess 301/302 redirect rules.
Trace redirect chains and spot wasteful hops.
Inspect a URL's HTTP response headers.