At first, confidence and a little bit of eye contact, not much in the way that the person is staring or seems desperate. But maybe I have noticed them and glance their way, they meet my eye contact and smile in a way that it's clear they are interested. For me it can be fairly subtle but confident signs that someone likes me and that they're aware I am interested in them. I like it when I feel that the guy knows that there is chemistry, they're not going to push me because they already know that there is something there.
Then if things move on from there, I guess very subtle body contact. I'm not talking obviously sexual hands on the hips, occasional bum graze. I'm talking about what is actually more sensual, maybe a hand on the shoulder or on the arm. Nothing that gives the "I am gagging for sex right now" image. If a man seems like they're chomping at the bit to get me home then it's a turn off, it makes them appear weak, out of control and desperate. I like to be with a man who is my equal, and sees me as that. Not someone who is either using me for sex or is so braindead that they cannot be patient.
With the right body language though, I melt! I'm one of those girls, if I don't want to sleep with someone or they give me red flags they will never get anywhere however hard they try. But if it feels right then I don't fuck around with games, I live in the moment when it comes to pleasure and experiences, so if it seems like it's going to be one I would regret missing, I would be unlikely to miss it. Unless there are consequences which make it not worth it. But to be honest, nowadays not many men or women come along that stand much of a chance.