1. Validate HTML
2. Validate your CSS
You should use W3C’s CSS validator tool to validate your style sheets.
3. Validate site links
Check broken links across the site with W3C’s Link checker tool
4. Cross browser compatibility
Check the site on multiple browsers with this tool (You may not have a MAC, but you can you can test the site Mac Safari
Even if it’s a simple static site, do them to make the site perfect.