How should I approach her?

Like she was any other girl. just say hi and start up a conversation.

So many guys get hung up on this whole thing of how to approach a girl. There's really only one way to approach anyone.approach them. It sounds so easy, but for some guys it's just so hard because you either fear rejection, and if it's likely you try to postpone it. Logically this doesn't make sense, but then again we've never really been know for our ability to be logical around girls.

If you want to tell her that you like her, your first move should be to start a conversation, then see how she reacts while she's talking to you. If she laughs at your joke, or makes flirtatious movements, of if you just have that gut feeling that she's digging you, ask her out.