Legendary coach Nick Bollettieri shares a preparation drill that every young player should perfect. Turning your hips and shoulders when preparing to hit the ball is essential because it automatically pivots your outer leg to the inside, helping your load power. 

"Even if [I] have to hit the most difficult ball, I have turned my shoulders which enables me to strike the ball with some authority," Bollettieri says. "Turn those hips and shoulders." 

Bollettieri's drill is simple, just repeat setting up your swing with a shoulder and hip turn, allowing your outside leg to turn in each time.