The current girl I'm after is what I would consider "out of my league" but I've grown confident and such enough that I can approach her.
First off, for guys...you just have to "not care"...by that I mean "don't care if you look like a goof doing so-and-so" or "don't care if you get a 'no'"...having that kind of attitude helps out a lot. Don't take yourself too seriously and you'll do fine...but don't come off as too cocky...a little is fine, too much is a turn-off.
Looks are the first impression...if you're a super hot girl and dressed super hot...you will typically be deemed "unapproachable"...especially if surrounded by fellow girlfriends who would "protect you". Only smooth guys can work in that way, but more often than not...these type of guys aren't the ones you want are they ladies? Especially at the bar/club.