Generalities

Uniformity /Accessibility

How will your page look on different systems (OS/Browsers) ?

Specifying fonts or sizes => CSS

Never use non standard HTML Tags

Can common browsers view your page

Do you include metadata (TITLE  tag and ALT attributes and others)

Try on several systems/plateforms

Safari, Firefox, Omniweb, Netscape Navigator, OPERA, Lynx ( text only ), MSIE. ..

Can search engines extract information from your page

Do you want them to ?