People can't help the way they send out a certain message by their body language. Sometimes they may even be completely unaware, until someone brings it to their attention.
I don't really think there is a technique in it though. You just have to watch people for a while, watch their movements that coincide with their words. Do they match? If someone says they aren't nervous, yet their foot is swinging back and forth 90 miles an hour, then ask them why they seem nervous, yet insist that they aren't. Touching is a big clue that someone could be fond of you. Crossing their arms could mean they don't agree with you. Not looking in your eyes while they are talking could mean they are intimidated by you and or nervous, because they are lying or uncertain with what they are saying *course it could also mean they have vision problems* Just sit back and observe people, you will soon see what they are saying and feeling without them even opening their mouths.
Good Topic
Magestica

