or say "hey, how's it goin?"
That's not weird, just an acknowledgement you see each other 20 times a day.
Then transition to hi.....then transition to saying something like "hey, have you seen so and so (someone you both know)? I've been looking for him/her" Even if she say "no" you're talking to her.
After that, you've officially talked to her, and can go from there.
That's a build up to a real conversation if I ever heard one.