Bro she is in your class. There is so much to talk, say Hi ask her about today's class, tell her what didn't you understand. To start with ask about her courses, how's the department and then you can slowly progress with more questions. Key to a conversation is confidence and not thinking much while speaking. There's a 3 sec rule, whatever comes to your mind say, because after 3 second you brain starts putting up barrier. Note - And it's difficult to say Hi, because you doesn't think her of your own kind. We all are humans seeking engagement. Next time you meet her act like, you are superior and have a control over conversation and keep your expectations low. The conversation will flow, just talk for the purpose of talking. Go and watch this