She probably doesn't notice you, unless shes flirting then try to get her attention and chat with each other. yet if nothing works the move on she doesn't like you then again she could be playing hard to get which is not very common
ok, I'm a girl and if he's talking to the girls friend he's making a BIG mistake because the girl, especially if she likes him back will think your not interested in her and interested in the friend....
Ask questions, and listen more than talking. What are her hobbies? Has she travelled anywhere interesting? What would a perfect day be for her? Who is your weirdest relative? What is that person...