Just ask her out. If there are a bunch of other girls chasing after you, no wonder she's being a bit cautious, eh?
Go out together. See if you enjoy each other's company. See if you get along. See if you're both interested in each other's conversation, have things in common (you know, first date stuff) then take it from there. If you have a good time the first time, try it again. It's not rocket science. What's the worst thing that could happen? You go out, you have a boring time. So what?
"The only thing to do with good advice is to pass it on. It is never any use to oneself." - Oscar Wilde