I go bare (but I'm only 19, so..), and add in some natural mascara, lip balm, lip tint, concealer under my eyes, and blush when I'm going out. Sometimes I use a bit of eyeshadow for shading and a highlighter to brighten my eyes.
The blush and concealer is Dr. Hauschka (www.saffronrouge.com), the liptint is Burt's Bees, the mascara is from Suncoat (http://www.suncoatproducts.com/) and the eyeshadow is from EcoBella, but I don't recommend them because the shadows don't blend well. I'll prolly switch to Dr. Hauschka, Suncoat or theorganicmakeupcompany.ca when I can afford it. The highlighter I use on my eyes is from Tony&Tina, but they've been discontinued. Too bad - it's a pretty highlighter.