Nonverbal communication is a largely misunderstood area.
While a powerful and essential component of communication and relationship building, it is not a magic wand.
My number one message to everyone when discussing body language, is that self-awareness always comes first. Be first aware of your own tendencies, understand them, and decide whether or not they are serving you.
The very reason we started our Virtual Sapiens Sidekick with a user focus, as opposed to a broader focus on audience engagement, is because of the power we can tap into through our own self-awareness.
When assessing other people, remember that context is king and a single behavior rarely leads to a sound judgement, but rather, to more insightful questions asked and overall deeper relationship building.