It doesn't matter too much, what matters is her attraction for you. HOWEVER there are a few things to avoid. For example, don't ask as if you're expecting failure. Don't be "super alpha" and say "we're going out, nowww, gooo, get to tha choppa!" but what I mean is, don't be like "hey, I was wondering, you don't have to, feel free to say no... But... Would you like to hang out some time?" If she is quite into you, then ****, not sure how much difference that makes, but if you demonstrate to her that you are too interested in her, she may reject you thinking she can do better, and that she can have you whenever she wants. Instead be direct and confident when you ask.
A good thing to do, if she says she wants to go anywhere, offer to go with her. One on one obviously. For example, she says something like "oh my god I really want to go to *super cool place*!", say "haha yeah that would be good, wanna go with me?"
Also something to remember:
All that matters is whether she'll spend time with you alone. If you ask a girl to "be your girlfriend", you have a much lower chance. Much lower. However if you ask to hang out, she may begin to feel something for you once you spend time alone and start talking more. You don't have to ask for a "date", it doesn't matter, you set the tone when you're out together. Ignore anything she's ever said to her friends about you if it's bad, or what she's said directly to you. It's all irrelevant. All that hearsay, it doesn't mean too much and you'll soon see that. Girl's change their minds all the time once you begin to take action.
Remember there's a reason why "dating" exists. Don't ever screw yourself over by asking a girl to "be your girlfriend", unless you know for a fact she is really into you.