First question; what is your intention of approaching her?

Second; is she still single or is she still with the other guy?

In any case, just walk right up and take the first approach. Regardless of your intention of pursuing her or just to make friends, you should take the lead.

Say hello, start topics that will be relevant to her or throw a couple of general topics to kick-off a conversation. Treat it casual, and you will be fine.

This post has been edited by Kevmeister: Jan 29 2015, 10:17 AM

1. According to 2, then you should just try to be her friend for now. Like my previous suggestion, just talk casually and don't make yourself sounding too nervous, and neither should you sound cautious. Just play it cool, treat her like a friend. It's hard, but it's a start.
2. If that's the case, refer to 1