If sounds are played automatically, provide visual notification and transcripts. Don't rely on color alone If you use color to convey information, make sure the information is also represented another way. Check that the foreground and background colors contrast sufficiently with each other. Make sure your document validates to formal published grammars. Use style sheets to control layout and presentation wherever possible.
Nest headings properly.
Make sure header elements are not used only for bold text. Only use list elements for actual lists, not formatting. Use lists properly. Clarify natural language usage Identify any changes in the document's language. If web pages are provided in various languages, contact the server operator to make them automatically available.