I’m not going to go into detail on this one since I just did a post about it in this post and decided it needed to be an RPR as well:  Effective Screen Layout: It’s about “where”, not “what”.

Basically, everything important needs to be in the area of screen from the left edge to the center. Anything right of center will usually be ignored.

Also, anything that is an image; pictures, graphs, tables, charts; will be the first thing the user looks at and they’ll also get a closer examination than any text… so make ’em count.