The "friends" thing can be a killer, dude. If you stick out your head, you just may get it chopped off and the friendship would be ruined. I got seriously burned like this during my AFC days, and ended up wrecking things with the girl, but I didn't lose the lesson. If you go too slow, and she's interested, she may think she doesn't have a chance and she could end up getting banged by some other guy.
I want to start by saying that the following advice is if the girl is firmly just in the friends zone with you. Of course it doesn't really apply if she's already interested in you.
One thing you don't want to do is rush it. You're walking in a minefield without a map, buddy. You're already interested in her, now she has to get interested in you, and that has to be done ON HER OWN TIME! NEVER EVER JUST COME STRAIGHT OUT AND TELL HER YOU'RE INTERESTED IF SHE HASN'T BEEN PREPPED FIRST!!
Start this process by hitting her psychologically. You have to plant it in her mind that moving to the next level with you is not something that's "weird" to her. Start this by saying little things to her that one friend usually doesn't need to verbalize to another friend because it's implied, but that at the same time a guy would say to his girlfriend.
When you're out with her, start by occassionally doing something like just turning to her and looking her in the eyes and telling her something like how much you respect her, or how intelligent she is, or how she's so much more prettier than this chick or that chick. Leave it at that. Say it like a friend, don't lay it on too thick, or all at the same time, because then she'll know subconsciously something's up and she could very well start pushing herself from you.
Don't forget to hold the eye contact a little longer with her, maintain the "hello" hug a little longer, smile at her using both visible teeth and your eyes, and don't try to act too cool. She already knows you well as a friend, so playing the "mystery" game" isn't going to work with her. Unless she's really experienced in this game, she won't notice what you're doing.
At the same time, don't follow her around hoping she'll give you a cookie. Hang out with other girls liberally, and let your target HB start wondering why she's feeling jealousy for a guy who's just a friend. Let your target HB meet these girls... you're "friends", after all. NEVER LET HER FORGET YOU'RE YOUR OWN MAN, AND NOT SOME DROOLING PATHETIC IDIOT!!
Building these emotions in her could take months if she's not interested in you in the beginning as anything more than a friend now. If she starts getting interested in you, there should be signs from her: friends always kino, so you may not be able to tell much from there, but her eye contact may become a prolonged stare. Also, you may notice she starts making short calls to you about stupid things... did she leave a book at your house?... how does she get to such and such a place?
I've also noticed something about girls when they start getting an interest in you. Make a note as to the time they call. You might notice that they call almost exactly on the hour, or on the half hour. A good round number. If they are nervous about calling you, they have to gather up the courage first. They'll look at the clock and keep saying to themselves, no, I'll wait another five minutes, etc., five minutes come and go, they get irritated with themselves for not calling, but when the clock goes to a new hour, it's like their psychological deadline has passed, and they'll call.
Just like a stray dog, you have to coax her in towards you if you want her to come to you... if you're too loud or brash, the stray dog runs off. If you try to reach out and grab the stray dog, the dog gets scared and runs. You have to make the stray dog think it WANTS to come to you.
It's getting late here, there was more I wanted to write but I'm tired. I hope this is useful to you. Any other guys have anything to add or comment about what I wrote?
