How can you like her if you don't know her? If you are going purely on looks then I would be surprised if any attempt at a relationship will work.
I suggest getting to know her first; find out her interests, spend time with her, let her get to know you etc...
Don't just go up to her face and ask her out - sure fire way to get shot down. And by "getting to know her" I don't mean follow her around everywhere with your jaw dropped and a daft look on your face. These things take time but if you want it to work long term, it's what you gotta do
If you're just after a one niter it's diff but PM me if that's the case