Responsive Website:
https://www.smashingmagazine.com/2011/01/guidelines-for-responsive-web-design/
https://www.w3schools.com/html/html_responsive.asp
Calls To Action:
https://topofy.com/website-call-action/
ADA:
https://www.w3.org/WAI/fundamentals/
Readability Score:
https://www.webfx.com/tools/read-able/
Google Analytics:
https://marketingplatform.google.com/about/analytics/
You want your bounce rate low and your session time high.