It makes since to be afraid of the answer you will receive, because it hurts to hear no...but you'll never hear the word yes if you live in fear of the word no...When and where do you usually see her?  Is there a time when the two of you are ever away from other people?  Just be honest and say something like, "I just really want to ask you out..." and see what she has to say.  It's way more scary BEFORE you do it, but you can ask her!