I loved body language by Allan and Barbara Pease. It is short, to the point and has nice diagrams.

http://www.amazon.com/The-Definitive-Book-Body-Language/dp/0...

100 times yes. This book is amazing for this[1]. You can skim it online[2], but I highly suggest getting a real copy. There are so many things to pay attention to, but one of the greatest realizations for me was that your body language can and does affect other people's, even if they are not aware of it.

[1] http://www.amazon.com/The-Definitive-Book-Body-Language/dp/0...

[2] http://www.slideshare.net/anhnguyet_hro/the-definitive-booko...