How to talk and approach girls?

K so i guess ill talk a bit bout myself so you can get to understand me.. im 15, 6'2, 200 pounds, people usually tell me im chill, good llistener, fun to be with, i always been told i have swag and good style from my shirts to my hats to my nikes. Ive got great grades but im not a nerd or anything... Im pretty social and have a lot of friends, ill admit i can pretty damn shy with people im not too close with and cant act like myself...its such a strange feeling,and especially with girls i like! F****! i have no idea how to act around them, i have a feeling i come off as awkard:/ So whats the secret to talking to girls? How would you approach a girl you dont know..because thats the only way ill ever get a gf cause i go to a gay *** private school so all the girls are uptight bitches and annoying! Pls dont tell me that "be yourself"bulls*** cause that hasnt been working lmao ill start being myself once we start talking. i just got this empty feeling inside and just want to be with girls..s*** has to change...sooo help me out?