CSS Tips?

I've been working on new custom themes for the FanMail website based on color schemes of various schools and organizations that share names with our first domains we are testing (Chargers and Mountaineers). For the most part, I've been changing colors on the templates I have already. At the end of the week, I was able to determine some things in CSS other than just the colors and started playing around with other variables. I've now done a couple dozen themes and my creativity is now encouraged enough that I'm getting frustrated with my incomplete knowledge of What the Hell I'm Doing.

I had Andy bring over his The Missing Manual for CSS, but didn't know if anyone else on the lovely flist might have any other suggestion for a CSS newb.