The lead character, Cal Lightman, is a great study in body language. I don't know the actor's name but I am impressed. He does this thing I call the "Lightman Flop" which is to say that he jumps up into the air and lands on people's couches in a sprawled position that says "I own this place" and also "climb aboard" to any attractive women. He also shows his distrust of various characters with a toothy "smile" that isn't friendly at all---it's more of a snarl, and he is showing his teeth as if to say "Look out, I bite". One other notable thing that Cal the character does is he is very relaxed, intentionally relaxed. Being able to shrug off tension, to grimace and then release the face, is something most of us could use some practice at. Watching his swaying walk and the way his mouth hangs open when he is listening carefully has me experimenting with new ways of relaxing myself, and of conveying that I am paying my full attention. One of the recent episodes in season 3 showed him training a cop to fool lie detection specialists, and the main tidbit I took from it is "relax your cheeks" and keep after it, to avoid showing emotions that you don't want to show.
There's a lot that is said out loud in this program to teach people about nonverbal cues, but there is more that is not said, it is simply modeled, and it is up to the watcher to identify it.