Girls: how would you feel if a guy told you...?

[Johnny]

"Hey, are you on Facebook? I don't want to talk to you only if we bump into each other".
Perhaps you should know she's stared at me several times (she doesn't seem attached to anyone) and we already talked once (which was very pleasant), but we don't share any classes (we go to the same Uni).
Or perhaps I should wait to tell her something like that?

[Sarah]

That sounds pretty good to me. If she comes back with "what do you mean" then you can start to flirt and so on. Talking online opens a lot of windows of opportunities, but try to meet up with her as well. Instead of just sending messages over Facebook suggest to meet up and hang out when the two of you are free. Good luck!