If you are restricted in neck rotation, you will have a hard time completing a full shoulder turn and you may take your eye off the ball.

Sit upright on a ball or chair, maintaining good posture and looking forward.
Slowly rotate your head to the right as far as you can and hold the position for a moment.
Slowly return to the start position and then slowly rotate your head to the left as far as you can and hold position for a moment.
Alternate rotating your head from side to side for 8 to 10 repetitions.
Do 2 to 3 sets.