Here is what I always put into my CSS file everytime when I start working on new project:
html, body, div, h1, h2, h3, h4, h5, h6, ul, ol, dl, li, dt, dd, p, blockquote,
pre, form, fieldset, table, th, td { margin: 0; padding: 0; }
The goal of reseting elements above is to reduce browser default styling. More extended version is presented by Eric Meyer on his blog. There is also Yahoo version of CSS Reset available on YUI Library.