Narrow and deep Quick to download a page of data. Looks more friendly. May take a long time to find the information they require, increasing irritation. Text You have little control over the fonts and the font sizes used, but even so, use them sparingly. Dont mix and match.
Backgrounds Keep any backgrounds simple.
Pastel shades are easier on the eye. Keep the colours light, rather than dark. Don't make the background .gif too large. Always ask yourself what the graphic is for. If it doesn't do any of these things critically assess its value to the page.