I look like a slut..?

With makeup, less is more. Don't use foundation at all, you're young enough you don't need it. If you wear makeup at all, only wear mascara. I recommend anything by Avon, they tend to look more natural. White eyeliner on your water lines and in the corner of your eyes can help you look more awake and fresh, which, believe me, is not what a slut looks like.