First, you need to train a strong-willed look. Parallel to this, train the inner spirit, calm and self-confidence. For a start, try to cause a feeling of control over the person, the superiority over him. Imagine yourself bigger, higher and stronger. Imagine that you are giving him commands and how he is carrying them out. Visualize and expect obedience. Your look should be from top to down, calm and imperative. By practicing this, you will feel the reduction of resistance and aspirations of the person to obey.