Hm, normaly I would post some corny chat up line that is sure to get you shot down...but today I'm feeling extra nice
The friend of a friend thang is a pretty good idea. You can discuss where you met your friend, and that leads down other roads of conversation. Get to know her, yeah, but don't wait too long, cos otherwise she'll just spring that 'But It'd be Like Going Out With My Brother' excuse on you when you do ask.