I started at a new school in September and went through a couple of silly crushes on girls I hardly knew, but know I have found a girl I am definitely interested in (a year older than me) and quite good friends with, and want to escalate the relationship into something romantic/sexual. She is gorgeous (that is widely acknowledged, not just me saying that) and popular, but not at all bitchy or cliquey, and many gorgeous popular girls are.

Anyway, after a slowish start at school I saw her at a party and we got on really well and I got a "hug close" and, while I didn't see her hugely often for the remainder of that term we were definitely pretty good friends.

We have got significantly closer this term, and she obviously has great freindly affection for me, as I do for her, and reasonable amounts of hugging have happened, which I imagine is good general kino. I think that the biggest danger for me is to fall into the "nice guy" trap, as I like her so much that I do genuinely want to be nice to her. I think I have gone some way in avoiding that however, by being one of the top athletes in the school (so I don't seem like a wimpish nerd, have a hot body (six-pack and everything), and I know that she does admire me for my sporting ability), getting so drunk at a party that I went to hospital (this was an unfortunate one-off, so please don't try to moralise about it, but it certainly has made me seem a bit more wild and dangerous than otherwise - but vulnerable at the same time (she wasn't at the party)), and generally being amusingly arrogant (mostly jokingly, and mostly to other people, not her).

She sent me an affectionate, friendly Valentine's card and I sent her a jokingly sexual one, with an ironically bad chat-up line (along the lines of "Roses are red/Get into bed"), which I think was a good way of making her think of me more sexually, but in a non-creepy, amusing way. A significant problem is the fact that she has a boyfriend, but don't think it's a particularly serious relationship, and hopefully they will break up, or I could tempt her away.

Anyway, sorry for the long post, and what should I do to escalate the relationship into something romantic/sexual?

Pull her on a night out. You were both drunk and it just happened. Keep repeating.

Yes, I'll certainly go for it if I get an oppurtunity. Any advice on what approach I should use? Also, what if I don't get a chance (e.g. her staying sober, her boyfriend being there, or just not being on a night out with her). How could I escalate the relationship in an unromantic environment, e.g. just around school?

Another issue is the day after seducing her - how would I make a drunken kiss into a proper relationship, rather than an awkward situation she wants to forget, and quickly go back to being just friends?

P.S. This probably isn't important, but I wasn't drunk at all when I got a "hug close" at the party last term. She was a bit though. Just wanted to clear that up now.

Truth is if you are bothering to tell us about 'hug closes' then chance are you're probably not going to go out with her - but by all means still try!

I don't really see how you can do this apart from that, just persistence. Kasabi wrote a great post on it, PM him for advice.

Is her boyfriend a bad dude? If not then why steal her? I don't see the reasoning for attempting to ruin someone's happy life to fulfill your own desires. Don't get me wrong, I have done my share of women that were in relationships, but that was because they reached out to me for a good time when their guy wasn't putting in the effort. That's a different story though.
I am actually in a situation at work right now where I dig this girl that just started. She has a boyfriend that she suspects of cheating on her. He is your run of the mill typical thugalicious dude that cares more about being "street" than picking up his girlfriend from work when he is supposed to. With that said I have no guilt in stealing her, so I am trying a method I read here a while back. I don't recall the thread but it is called the Straw Man Tactic. Basically you put her boyfriend on a pedastal of being such a great guy with impossible to meet standards. Supposedly she will see that he isn't really that great of a guy on her own without you having to stoop to AFC tactics to try and steal her.
Its been ok so far, but my co-workers make it difficult because everyone sees the attraction between us and they all keep trying to help me out in the worst ways.