Reality. You say one lie (that you are bold-faced aware you are saying), and you have just changed the game. You now have to keep track of the lie, never forget it, and know that that lie is what part of your potential relationship is now based on. For she will believe you. And one day, if you are both lucky enough to get involved, she will find out. And she will dump your ass. Or do a LOT of haranguing and how-could-yous.
In the same respect as you will be yourselfnervous if you are nervous (some girls find that adorable); clumsy if you are clumsy (some girls find this endearing)you will also remember that the girl you seek to impress might not be the one for youno matter how close a next-door neighbor she is or how many years you all went to the same football games and movies. Do not bother bartering above your station if she is not the type to date your type.
Confidence. Dont think yourself unworthy of every woman who walks into study hall, either. Try, please, TRY to strike a healthy balance between Ah, me, (ala Eyore) and the cock of the walk. We do not know how to handle either of you. WE dont know what to do with a whimpering oneother...