The hand leads the motion. Make sure that the elbow stays down while the shoulder and hips turn forward, keeping the chin down as you punch (rolling the shoulder up as you hit the target). At the end of the punch, the fist rotates to about 45 degrees (varies by individual). The striking surface will also vary by the type of punch (fist, palm heel, eye strike). Always punch through the target (not just the surface) and recoil immediately!