Need some girl help. How do I get her number?

[Go]

I work with this girl that is really cool and I think I'm starting to like her. I'm in high school and she does not go to my school, so I only see her on the weekends when I work. I wussed out last weekend and based on this week's schedule I will not see her. So I was thinking that maybe I could ask her via Twitter and just tell her to Direct Message it to me, or I just have to wait a week and a half, if we get scheduled together.

Input from girls would be great! Other suggestions are welcome!
I am gonna clarify really quick i'm asking whether I should ask over twitter or wait till i see her at work. I am going to ask her i just don't know when/where.