I found an article a while ago by Adrian Senior called CSS: Getting Into Good Coding Habits. This is an excellent article, but the part I have found very useful is where he discusses removing the browsers default settings. I have reproduced a slightly modified version below. I now use this as a starting point for stylesheets on evey new site I develop:
html, body, ul, ol, li, p, h1, h2, h3, h4, h5, h6, form, fieldset, a { margin: 0; padding: 0; border: 0; } body { font-size: 100.01%; /* Fix for some browser bugs */ background-color: #ffffff; } h1, h2, h3, h4, h5, h6 { font-weight:normal; font-size:100%; }