All you gotta do is become friends with her. (Yes, friendzone the girl) once she's comfortable with you, walk up to her and wink. Then lean in for a hug and once your arms are around her, lift her off the ground a little bit. That will drive her craaazy.
Try to connect with her in different ways. Whether it is through a favorite song or band, or just telling jokes that make her laugh. Try to make her feel special and important. Also asking a girl out on a first date and making it special is pretty romantic. Although that is after you get to know her.