Make her laugh and smile. first of all keep in your mind to be honest, don't try to flirt, show sincerity, sympathy and listen all her comments about any of her matter then try to solve her problem...
Just ask her about her interests and what she likes and doesn't like.Who knows,maybe you and her might have a lot in common.
well im thirteen so
I would say based on personal experience...
to impress a girl...always show her your natural talents or where are you good at without making her feel your a boastful type of a dude...be natural! :)