you smile and say hi, 90% percent of the time she will do the same, if you see her often like at school, just say "hey i have you for class but I rarely talk to you, my name is _________ whats yours? then talk about for example or a good starter, "who do you think would make a good president?" then from what you know you improvise, that way she knows you're friendly, approachable,intellectual. tease her a bit she laughs and chats more than you;re good to go and if you can get her number thats even better, tell you what you might want to read up on a new thread call "HEY YOU READ THIS". Hopefully I helped you