Usability Examples
Typography
  Use boldface sparingly
  Avoid italics altogether
  Avoid using all caps
  Use sans-serif fonts
  Avoid underlining

Miscellaneous
  Avoid horizontal scrolling
  Avoid animation
 Alignment
  Left justify text
  Avoid double spacing
  Top align text

Color
  Use light backround colors
  Avoid using different font colors

Avoid using all caps
EVEN IN TITLES, ALL CAPS SHOULD NOT BE USED. CAPS ARE HARDER TO READ BECAUSE ALL THE LETTERS ARE THE SAME HEIGHT. USING ALL CAPS ELIMINATES THE VISUAL CUES THAT ARE PROVIDED BY DIFFERENT SIZED LETTERS.

Information was taken from "Building Effective Web Sites" by Dr. Frost and Judy Strauss