Learn to put away any overhead within 5' of the service line. Practice overheads.
Normal first volley is just behind the service line, to just inside the service line. If you hit a strong, deep, and penetrating volley from there, move in another full step. If you hit a weak sitter volley from there, move in TWO full steps. If you hit an average volley, stay in position and anticipate a passing shot, you moving forwards. If they lob, you ANTICIPATED the pass, not moved forwards, and now standing at the service line.
Learn to hit overheads.