You should do whatever it goes with your personality, if you are a Mr nice guy then do it, don't change becasue of a girl besides when you say or do something that doesnt' go with your personality it looks fake and most girls can feel that.
I wouldn't recommend to try it with your girl at your school, just think what might happen if things don't work out. There are millions of women out there, much better if you try it somewhere else.
Here you have some tips to improve your daygame in case you need it.
https://www.youtube.com/watch?v=BWeQJmd ... 4OKeDCWlQb