I can't speak for all girls but generally girls dont give a fuck about what you look like.. so long as you dont look like a pig your fine.
All they want is someone to talk to.. to understand where they are at..
At times it is difficult around your peers..
perhaps if she is in your class.. or has some study..
say something like do you want to grab a coffee and go over those notes.
Then when you are having a coffee have a chat..
and shut your mouth and listen..