The backswing is probably the most important part of your swing. Without a backswing and a shoulder turn that is fundamentally correct, it is almost impossible to be a consistent ball striker and stay on plane.
So how do you develop a backswing that will allow you to strike the ball solidly every time?
First of all, make sure you have a good grip.
The proper grip will allow your hands to be in the proper position at the top of your backswing.
The proper position will have your top hand (left hand for right-handed golfers and the right hand for left-handed golfers) lined up with your forearm. The angle of the shaft in relation to your forearm should be at 90 degrees.
Second, have good posture at the address position.
Posture is your spine angle. Your spine angle should be about 45 degrees at the address position, at the top of your backswing and on the through swing.
A good way to check your hand position on your backswing is to take the club back to a position where your left arm is parallel to the ground and make sure the back of your left hand is at 45 degrees.
On the through swing, do the same thing and check to see if the back of your right hand is at 45 degrees.
A good backswing will produce quality shots.