One of the first things I check at the start of every lesson is how a player sets up to the golf ball. The address position has a huge effect on how the club is moved and thus the overall swing pattern. There is no one way that is universally correct for every player to correctly address the golf ball, but some fundamentals consistently apply for all of us.
When the club comes into contact with the ball most players correctly recognize that the sole of the club should be flat to the ground at impact. This will mean the sole of the club creates a divot that is equally deep on the toe end of the club as it is on the heel end. Thus it will be easier for the club to stay square through impact and give you a better chance of producing straight golf shots.
Unfortunately, many players take this idea a step too far and try to set the sole of the club flat on the ground in their address position. This is not correct. As you swing the club into impact the hips have rotated and there is more weight on your left leg than the right as you pivot around the left leg. In doing this the hands enter the impact zone in a higher position than they were at address and it is at this time the sole of the club will be flat on the ground.
If you address the ball with the sole of the club flat on the ground, you will create too much tension through the wrists and forearms, as well as setting the wrists in a position which will make it more difficult for them to hinge correctly in the backswing. A lack of wrist hinge can lead to a variety of problems including taking the club away off plane and not setting the club correctly at the top of the back swing.
In an athletic address position the arms hang comfortably from the shoulders with a slight cocking of the wrists as you grip the club. The toe of the club should be off the ground slightly, with the club resting more on the heel of the club. From this set up position it is easier for the wrists to cock correctly, starting the club on plane and setting the club at the top of the back swing.
A simple check to see if you have the club resting correctly on the ground at address and thus the wrists are well set, is to take your normal address position on a hard surface like your asphalt driveway. If you are setting up correctly you should notice the toe of the club is off the ground and the club is resting more towards the heel. If you are able to do this exercise indoors with a mirror to check your wrist position you should notice an angle between the forearms and the shaft of the club. If this is a straight line then the wrists are not set correctly and you should also check how the club is lying in the ground.
By ensuring you have the club resting on the ground correctly at address can solve many back swing problems. So be sure to take a few minutes and check this aspect of your set up as it will increase your opportunity to make a good back swing.