Continue ti be close friends and don't rush things. Usually boys should ask out the girls. How old are you? The circumstances are different by age. Don't worry, be yourself, and flirt a little bit. If you want tips, go to eHow.com! Dont try to be too flirty but continue being close friends! It will work out.
Sometimes you have to take risks. I dated one of my good guy friends and it ended very badly. But, it can still be the same if you make it that way. You have to say how you feel. Talk to him about it. See how he feels on it.