when I say "be direct" I just mean don't be scared to approach girls and ask them out. Don't sleaze over like "baby I wanna be on you" but strike up a conversation and if there's a vibe (trust your instincts) then don't be scared to invite her out for a drink or whatever (I realise you're kinda young for that but substitute drink for movie, roller disco, whatever it is youngsters do for fun these days).
Getting shot down happens, and it won't kill you if it does. Take it like a man and don't get all arsey about it. If she says no just smile and say that it's cool, then move on. Think of it like this: if she says no to you now, that's not to say that she'll say no again if you bump into her in a few weeks/months/years, so don't be a dick about it.
I assume because you've done some modelling that you're a good looking kid, so you're in a better position than most to do some ladykilling (metaphor; please don't actually kill any ladies)