1. Site speed
Check the size of your page sizes and their load time. You can use Google’s own site speed testto do this. Site speed is a ranking factor, so follow any improvements Google recommends as closely as you can.
2. Mobile friendliness
Is your website mobile-friendly. Frankly it’s very difficult not to building a multi-device compatible website in 2016, but just in case, here’s a handy checklist to ensure your website’s mobile-friendliness.
3. Compatibility
Check to make sure your website’s pages render well in common browsers. Browser share is a moving target so to help prioritize efforts, here’s a site that continually examines it.
4. Fonts
Sometimes font codes get dropped into a page inadvertently and make a letter or a word look funny. Check to see that the formatting is consistent, and look for odd blips in the copy.
5. Navigation
Test the navigation to breaking point. Make sure every single possible journey through your website leads to wherever its meant to without any broken links or wrong pages.
Makes sure your on-site search works, and it delivers accurate results, and if there are any zero-results that you’re providing navigation to other relevant pages.
A part of the article posted on ClickZ here.