Important commands are displayed as buttons, not links. For example “Buy” or “Pay” is a button, not a link.
Links are easily recognizable. They look clickable. Items that aren’t links don’t look clickable, for example underlining text is avoided.
Color. Visited links color is different than unvisited.
There are no broken links. Check with e.g. W3 Link Checker.

LAYOUT

Important content is displayed first.
Site is responsive. Works with different screen sizes. There is no horizontal scrolling.
Related information is grouped together clearly.
There are a minimum amount of pop-up windows.
Consistency. Page layouts are consistent across the whole website.
Pages aren’t cluttered. There is enough white space to support scanning.

ERRORS

Browser compatibility. Site works in various browsers. Check with e.g. the Browser Shots tool.

• User testing. Testing with target users is done at different stages of the project. People who weren’t involved in developing the site conduct testing. Use e.g. the free Peek tool to get started with user testing.
• Error pages. Site has custom 404 and 500 error pages.
• Security. Site has an SSL certificate. Check e.g. CloudFlare’s free Universal SSL.

FORMS

Simplicity. Only absolutely necessary questions are asked in forms.
Long dropdown menus are avoided. Instead users can input text, which is validated on the

• backend. Also, long dropdown menus are error prone to users scrolling with the mouse.
• Fields are labeled with common terms, e.g. Name, Address (supports autofill).
• Form submission is confirmed on e.g. a confirmation page.
  Error messages are shown next to the input field, not just on top of the page.