If you are looking to use YOUR body language to enhance your magic, get Juan Tamariz's The Five Points in Magic. If you are looking to figure out other people's body language, get the first book by Navarro. The other two books look like simplistic self-help books that try too hard. If you are trying to become more comfortable in talking to people, get Leil Lowndes. Still, the best way to communicate better with people is to just talk to people, ask them questions about themselves, smile when you talk and just be a nice guy.
In magic performance, much of what we do comes down to belief. As magicians, we need to believe the coin is transfered to from the right hand to the left hand even though it remains in the right hand. That is done by first practicing doing the actual transfer. If you get the feel of the actual move, then when you learn the sleight it should look and feel very similar. Then you need to practice the sleight. As you practice it, repeat the belief - "I'm putting the coin into my left hand." Then practice the move while talking out loud (preferably your presentation, but receiting poetry probably works just as well). As you are talking and doing the sleight think the belief "I'm putting the coin into my left hand." When you perform, you will be saying your presentation, thinking "I'm putting the coin into my hand" but through magic the coin isn't there because your muscle memory does a false transfer when you think "I'm putting the coin into my hand." The audience will see your nonverbal actions but they will be consistent with the belief that you are putting the coin in your left hand.
When I do my cups and balls routine, the final loads really just appear. My brain thinks "I'm going to pick the cups up one last time, show them empty and then put the empty cup on the table." My muscle memory picks up the load from my pocket and puts the load into the cup. It is so automatic and my belief is so strong, I don't remember doing the load. So, I'm actually surprised when I pick up the cups and the load is there.
