When trying to establish a pre-shot routine and the importance of the address position always remember to GASP – Grip, Aim, Stance, Posture.  In order to swing all of your clubs on plane it is essential to establish the correct posture.  Posture is the correct tilt to your spine and the right amount of knee flex. 

In order to establish correct posture, you should stand erect with the back straight and the chin out of the chest.  There should be a bend at the waist so that the shoulders hang directly over the toes and the knees are over the shoelaces.  Your hips should be directly over your heels and the weight should be on the flats of your feet.

From the correct posture, your shoulders should turn around at 90 degrees to your spine.  Turn around your spine.  Do not let the bend at your waist change.  Your hips will also turn so that the angles of your legs, established at address, stay constant throughout the back swing.  By turning around your spine, you maintain your correct posture—your body and leg angles—and as long as your arms do not do anything independent of your body, the club will automatically swing back and up on the correct plane.

If you stand with a posture too erect, with a straight back and over flexed knees, the shoulders will turn too level to the ground and the club will be swung in too flat a plane.  This flat plane will produce a lot of thin or even topped shots.

If you bend over too much at address with straight legs, the posture becomes too slumped over; the shoulders tilt too much in the back swing and this produces a swing in too steep a plane.  You will hit a lot of fat shots, hitting the ground behind the ball.

However, from the correct posture the shoulders will rotate at right angles to the spine.  This allows you to swing the club in the correct plane—not to flat and not to steep—and you will make contact with the bottom of the ball and then take a slight divot, which is the ideal situation.  Remember: Stand in the correct posture...and turn around your spine.  Maintain your posture throughout the swing and you will always swing on plane.