Even if she doesn't admit it, every girl has some type of sensitiveness.
Mentally may I add.
With the stereotypes and social media beliefs girls are told, it is easy to give off signals to make sure she knows.
It's like a 6th sense you might constantly use in high school especially.
With the right words and the right body language you're in. (Not like that)
Girls like to feel important, so smile at them. :)
Make them feel important. Wanted. This is a cruel world we live in, might as well try making it a brighter place.
Give her random compliments (Try not to make it too awkward?)
On different occasions girls like to do their hair in a way they think is cute or different. If you notice an outfit that you take interest in let her know :)
Tease her. In a cute way. Ya never know when she's having mood swings. So the safest route is to either ignore what I just said or make it cute.
If you know and are friends with the friends she so happens to be with, (That's a mouth full) joke and tease her in front of them. For one it'll show her friends that you're likable, and two it also gives her the hint that you are willing to be with her no matter what you or her is doing.
The golden hint that I can give you is to treat her differently than your friends that are girls.
I hope I helped in anyway.
Maybe not. I'll improve and edit this eventually :)
Vote, Comment below? Let me know how I did, anything you would like to add on?
P.s I'm not this full of cheese :P
~kaya