Everyone uses body language, and as far as I understand it everyone reads body language to a certain extent at least on a sub-conscious level. I notice a few things consciously myself. When I'm debating with people at school and I'm sort of winning.
I see that alot of the people I'm debating with start bitting their nails. Also when I'm in a Karate class and someone walks in and starts watching us break stuff and shout really loud they cross their arms with their fists usually closed, this appears to be a sort of defensive thing. I've read a little bit on this subject and one way to pick up on this stuff is to watch televison with the sound off and take notice of how people are moving.
Well I hoped that helped.
Hornet.