General points:

• follow widespread user expectations
• keeps things simple and fast
• keep download times as short as possible; enabling zip compression on your server is almost always a good idea

• don't hard-code font size
• don't disable the browser's ability to change font size
• don't hard-code absolute pixel sizes
• rendering must be reasonable for a wide range of screen resolutions
• if layout is based on tables, use several tables instead of one large one - the first table will be rendered while the others are still downloading
• if using tables, use the COLGROUP and COL tags to define both the number of columns and their relative percentage widths - this allows a smart browser to start rendering a single table before it has received all of its content
• include width and height for images - allows faster rendering
• include ALT text for images
• break up blocks of text with lots of white space

• use standard colours for links
• avoid horizontal scrolling
• don't use frames
• half the users will go directly to the search box, without examining the structure of the site in any way
• store the text entered by users into the search box, for later examination
• the attention of many users will initially go to the center of a page, not the top
• high quality page titles and metadata are important for bookmarks and search engines