What do girls like to hear from a guy?

There's this girl in my class, and I've liked her for a while now but I'm shy, she means alot to me like I would much rather do a completely mundane activitiy with her then do something exciting with my friends. I think she might like me to because she acts very flirty, how can I sort of imply that I like her and what do girls like hearing from guys(compliments etc)