Just go for it

Sometimes, the best way to ask a girl out is just to remind yourself that you've got not much to lose and a lot to gain.
I'm a personal fan of the 'just try it and see how it goes' attitude as it means you can have lots of confidence simply because you're doing what you want to do! :D
After all, what's the point in wasting good opportunities? You'll only hate yourself later if you had a chance but didn't take it..