My advice is to make it extremely clear that you want her without saying it. Flirt excessively with her, touch her in non-threatening ways whenever you get the chance, hold eye contact when talking. Always make sure she has fun while she is with you. Limit the amount of time you spend with her so she always wants more of you. If she is having fun with you she will want to be around you more, just give her limited doses of yourself and it will drive her wild and she will have to give you attention in more extreme ways. If she doesn't respond to you in a sexual manner, just start drifting away and if she doesn't try to get your attention again then just move on and break off contact.