This sucks - I know, I'm a shy guy - but just go for it dude. The worst that could happen is that she says no.

(Or, the worst that could happen is she lays sexual harrasment charges against you - but go for it anyway.)

Remember that chicks love confidence so just the fact that you approach her will impress her, even if she says no. That way you 'advertise' to other potentials, so picking girls up gets a little easier. Its a win-win situation!