Dialog — One immediately thinks "she said" or, "he asked" or, "they yelled." It is the dialog tag denoting who is speaking. But there is more to dialog that just speaking. Our bodies speak to others without us even thinking about it. Consider:
Without too much more description, you could fill in the rest of the mental picture: jaw slightly jutting out and eyes narrowed to slits. You can visualize the expanded chest, bulging arm muscles — the show of power, obstinance, and determination.
Now, let your character speak … even the simplest of terms and it will carry weight.
Body language is a tricky thing. Depending on the situation, each action can be read differently. Consider the above, arms folded over the chest. In that situation, it notes belligerence, but if it was your mother calling you home because you did something you shouldn't have, it would denote being ticked. While another situation would be listening to your boss rant about your work evaluation and your disgust with his reaction. In all three situations, the person is blocking out people, but each with a different end result potential: threat, control and indifference.
Consider two separate scenes: First, John is sitting in Human Resources, learning about a possible position.
Now, John is standing before the double doors leading into the boardroom where all the partners of the law firm await his arrival.
Body language can be revealed in several ways:
Now I shall reveal the secret of using body language.
Body language allows you to set the scene and show some of what your character is doing. But … a very big BUT … you don't want to overwhelm your reader with all the possible body actions. Allow your reader to fill in some of the spaces. Never, ever assume your reader doesn't understand or know. True, they may not, but if you've written it properly, the reader should be informed enough to figure it out. Give the reader some credit.