Well competition is always a thing to consider. You have really two options here.
1) Play it safe. Talk to her, chat her up, act more like a friend to her. Laugh, smile, say nice things.
2) Take the risk. Ask her for her number, when she gives it, ask her when would be a good time to call. If you have her number, ask her if she's free one day, and ask her if she would want to go somewhere, maybe to a movie.
I know you're considering a lot of things for instance how she's a bit younger than you. A good thing to consider.
Remember this, you can quote me on this.
Good things come to those that wait, but better things come to those that fight.
