When you speak before any person, before you start speaking, your body language is something that creates the initial impact on the opposite person.
Whenever you speak or listen, stand still. Constantly moving or swaying creates an interruption in the conversation. If you stand still but relaxed, it throws positivity from you on other person and you look confident.
Keep an eye-to-eye contact. While you have a conversation with a person, maintaining eye-to-eye contact with the other person makes the conversation deep and clear. It means that you and the opposite person are focused in the conversation rather than some different topic.
Movement of your hands, shoulders or torso much is well-timed. If you constantly keep shrugging your shoulders or move hands, it may create disturbance in your personality. Move your body parts timely and when needed.
Your body language is the first and foremost impression of your inner self.