I recommend the Tea Tree Oil, too! I love that stuff. Right now, I am adding a few drops to my cleanser to help kill the bacteria in my pores. I use Clinique's Mild Soap, which is fine and gentle but doesn't do much to help fight zits. So I just lather up, and add a drop of Tea Tree. Sometimes, if I feel a pimple trying to pop up, I'll apply it directly onto my skin. This can be a bit harsh, you may also dilute it a bit with water.
Another thing you can do with Tea Tree oil is to add a drop to your toothpaste. This will naturally help kill the nasty bacteria in your mouth, without using chemicals.