I think the OP is just trying to figure out how to act yourself, not try to hard and get her off the pedestol because that
gives you the best chance.
I would agree that for a lot of people the minute you think a girl may be interested in you, you start acting weird and trying to hard because you want to "keep the interest" but thats usually when you kill it. Even if you were the one who got her interested
in the first place you sometimes think, "wow, it worked" then you go ahead and fck it up because you change as to keep it going.
But you have to find that right balance of flirting with a girl and trying to get in her pants WHILE being non nervous, non outcome dependent, not really caring. Staying totally in control of yourself and rolling with the gauranteed sh*t tests that are sure to come.
Assuming she is a friend who doesnt want you is NOT what you should be doing though. You're allowed to like a chick and want to bang her just don't take it so seriously.