You may not have noticed, but your body speaks your mind, even when you don't. Every gesture you make, ever stance you take, lets on how you really feel about something. To know where a relationship is going, for example, check out his/her (and even your own) body language...
"I like this one..."
The more you mirror each other, the more in accord you are. The more often you look each other in the eye, the more emotional contact you make. Bodies held the same way? Heads tilted, hanging on every word? Hands touching affectionately? Legs crossed towards each other? It's like Cher said in Clueless, it's "an unequivocal sex invite."
"Mmm... I don't know."
Ambivalence makes itself known in the little things. Arm around her shoulder but his head turned away. One leg pointing towards her, the other sliding off. He's attracted to her, but he may be scared of being tied down. She's leaning towards him at the top, but her legs are ready to walk away. Dependance and independance are battling it out.
"Uh-uh. No way."
Do exactly the opposite of whoever you're with and hidden (or maybe not so hidden) tensions are revealved. Legs crossed away from each other? Eyes anywhere but on each other? Hand over mouth or ear? These are clear signals that you're not impressed with what is being said and/or you want to be somewhere else --or your date does.
Still not satisfied? Check out my flash body language road map and get some tips for being more approachable, whether or not you're on the prowl.