Want to play like a professional? Try starting all your strokes and volleys with a "unit turn." What is a "Unit Turn?"
Think of the racket as welded to the center of your chest. Then remember not to move your arms. This will force you to take the racket back with your shoulders and chest, not your wrist and arms. Your entire upper body will pivot, forcing the racket back. When your shoulders stop, stop the racket. This will prevent excessive back swings and "double" back swings. The future of tennis will be the "unit-turn" for the upper body and less turning with the lower body. This will create more power with less effort.
Good luck on the Court!