A girl who is not mysterious to you, you do not want.
Lio.. if she calls you (I am hoping you did give her your telephone number), be sure to get her phone number from her as well. It is likely you will be expected to be the person to call next time.
My problem is that I don't like calling people without some reason or idea.. I mean.. a reason to give them. The thing is... you don't need to give a reason. You both already know the reason most likely.
You know the call is going well if the reason you have to go is because your roommate (or hers) is complaining about you being on the phone for two hours.
To me phone conversations are the most awkward.. you can't really tell how someone reacts over the phone.. well, not as easily as in person.
Walking her home or to the bus is good too. Be careful with that one because when you're done with the walk, there is that awkward moment where neither of you know what to say or how to say it.
Don't stalk her either.. don't conveniently run into her. There are girls on my floor that have funny stories about that happening to them. One though is a complete lie because I can't believe anyone would conveniently run into her.
I like the more forward/direct approach:
Stare at her boobs when you are talking to her. That will signal to her you like her, and she will be highly flattered that you like her chest as much as she does.
Periodically motion like you are going to cup her breasts with both hands, but stop when your hands are a few inches away. After you do this a few times, she will grab your hands and pull them to her chest.
After you have exchanged more than 10 minutes of conversation, unzip your pants. She is now ready to suck your dick.
If she asks you any question, always make a comparison to whatever she is asking about to your balls. If she asks you about dinner, compare dinner to your balls. If she asks you about an assignment, compare the assignment to your balls. If she asks you about her new hair style, compare it to your balls. You get the idea
Whenever possible, stare at her seductively with half a grin, grab your grotch and nod.