Subtlety
A great thing about escalation is that it doesn't have to mean leaning in for the kiss. Going in for a kiss is after all a very bold all-or-nothing move, and hence it's easier to get turned down. Still it can be a very powerful move when the conditions are right, though it's probably not the best move if you're in a social setting or her friends are nearby.
Luckily, if you don't feel up to it, there are ways around it, and there are ways of escalation to find out if she's ready that are much more subtle. Also, knowing that you don't have to be overt actually makes it a lot simpler to escalate.Personally I found this out by accident back when I was a student, but also 60 Years of Challenge has explained this one particularly well. In essence, all you need to do, is find out if she likes holding hands with you. A slight touch can be enough. If she strokes or squeeses back, then she's into you, and you can safely escalate further if the situation allows it. But even if the surroundinc circumstances aren't perfect, if the hand escalation went well, she'll be much more likely to comply with other stuff also, so just invite her to come with you somewhere more private. Many say you have to lead her since that is more alpha, but I find that inviting her is even mroe powerful as it instigates a psychological effect that the Professor and researcher in Psychology, Robert Cialdini, calls Commitment and Consistency. Thus if she commits to something, she's more likely to also go trough with it. Another reason to not bother dealing with women that aren't fully into you.
The great thing about such subtle moves is that you can do it in almost any situation, and only you and her will notice. That it happens in a social setting makes it extra exciting because you have a secret together. It creates a kind of bubble for the two of you that binds you closer together. Best of all, you won't feel half as let down if she doesn't comply with your move. It's all under the radar, and you don't need to feel either hurt or disqualified about it. In fact, even if you didn't get into the warmth the first time, you still get more chances as not getting compliance on a subtle move isn't the same as being verbally turned down.
Also, flirting with her in such a hidden way tells her a very positive thing about you: That you're discrete and probably experienced. In turn that makes you safer to have casual sex with since she knows that she won't have to worry about you blurting stuff out to friends. Also, since you seem experienced, she knows that she is less likely to have a nagging and needy guy on her shoulders afterwards. Not that these things exclude the possibility of something more serious. If you want, you can still go for that, and in fact doing it makes you that much more of a good catch to her.
Next: RFE Part 2: Why Escalating Is Sexy (coming soon)