it was said best above, balance is the key.

don't come off as too cocky, but at the same time don't lack self confidence. carry yourself in a way that tells her you know what your doing.

when your flirting, compliment her, and make it sounds good. but dont take it too far where you come off as creepy. and be careful what you compliment about.

from my experience, girls enjoy at least some challenge. don't throw all of your self out there from the beginning, then they will have nothing to work for and i've seen that go bad for a lot of people.

like i said, texting at first, before you make the call will help break the ice and make it easier when you call her.

don't wait too long, but don't call her 5 minutes after you got her number either.

and if she has a boyfriend then she could be one of the crazy girls who love knowing they can get any guy they want, but only go for the one guy that doesn't want them and just plays head games with all the other guys.

hope that helps a little

oh yeah, and dont use myspace until after you've already talked to her for a while. thats a lame way to go about things. stick with texting/calls.