To achieve a clean hit on the ball consistently you need to get your head up while keeping your eyes focused on the ball well after contact with your head still.  Our eyes are our cameras so if we are not in focus and move our head, the result is a blurry picture, and a not so pretty serve.

EXERCISES
1.  Use ServeMaster to learn the timing of lifting your eyes and head.  Also practice balance while looking up.
2.  With your eyes to the sky, go through your motion without hitting a ball.
3.  Combine the pronation drill with your head up.  You should not see the ball land on the other side of the net.
NEVER LOOK DOWN ON A SERVE