As a point of interest, If you continually hit the ground before striking the ball rather than striking the ball before you hit the ground, the most obvious reason is that you are allowing your hips and your head to sway away from the original address position during the back swing and then not returning the hips or the head back to the original address position, or alternatively, you are not watching the ball right up to the point where the club head strikes the ball.
Therefore you must hold the hips in the original address position throughout the complete back swing movement, or to clarify, the hips must not sway away from the original address position for a fraction of an inch, if you can make a back swing in this manner it will cure this problem.
However what in equally as important, the upper body must remain at the angle that it was set at the address position whilst the shoulders rotate into the back swing.
In addition, the head must remain in the original address position throughout the back swing movement.
