CSS Reset provides a good starting point.
“The basic reason is that all browsers have presentation defaults, but no browsers have the same defaults. (Okay, no two browser families—most Gecko-based browsers do have the same defaults.)”
http://meyerweb.com/eric/tools/css/reset/
http://developer.yahoo.com/yui/reset/
http://stackoverflow.com/questions/116754/best-css-reset