I can tell you some things I've done when I was interested, that may help you read some signals.
In general, eye contact, and hair twirling, and her touching your arm are good signs.
More specifically, though, you are in law school, right? I can tell you from personal experience, that if a girl comes up to you at school, leans in real close, smiles a lot, and asks for your help on a case you are both dissecting for a class, or help studying for an exam, she probably likes you. That started me on a long term dating situation with a 3rd year when I was a 1st year.
I also remember a dinner business meeting once where I made regular eye contact with a guy across the table while I played with the pearls I was wearing to get this attention. He definitely got the message I was interested.
Does that help at all?