The great actor, James Cagney said “Plant your feet and tell the truth.”
Self-awareness is the most important part of body language. Unless we have serious body language issues it’s not something I often tell my clients to focus on because it puts them in their head. As an actor I’ve learned that when the director tells you to do a specific body movement or posture, the direction itself puts the actor into his head. Being self-conscious consistently introduces more problems than it solves, whereas being natural and flowing in your own unique way allows authentic and effective body language to emerge without second thought. Proper body language will not make you comfortable in your own skin, but being comfortable in your own skin will almost always manifest as proper body language.
Listen to Her (not the voices in your head)
There are no lies in the language of the body. Your body can only represent it’s own expression. Any attempt to force a different expression will sabotage itself, because it contradicts the effortless ease of natural body language. Men can become hyper-sensitive about body language because they want to get it right, which then puts them in their head instead of the moment, not listening to the girl. The way out of this self-sabotage is to listen to her and respond off of what she’s saying rather than from the negative voices in your head. If you’re really listening, your body language is going to be just fine. By listening, relating, and responding to her, you will be in a more relaxed state, which will automatically come through your posture, gestures and expression.