It depends really what you're best feature is?
I love clothes so won't really have this problem but for example if your legs are your best feature you could maybe buy some heels (say in a tan colour, or even red which would go with most things), then maybe some short shorts , or a skirt (for clubbing).
A couple of nice tops, some casual dresses, ermmm and some nice fitting jeans, and the main thing is accessories! Get some nice beads/bracelets and earrings that way if you just want to wear jeans and a top it'll look more dressy.
If you're not a girly girl though don't force yourself to be one, students dress down a lot, unless you're going to a really posy club with a 'smart' dress code.
Probably didn't make much sense there!