Setting the golf club correctly at the top of your golf swing allows you to make a very efficient movement during your golf swing. In doing this, you are able to produce the most club head speed and therefore achieve maximum distance with your golf shots.
In order to set the club correctly at the top of your golf swing, work on the following. As you swing the club away from the ball, you should rotate your upper body 90 degrees to the right (if you are right handed) of where your shoulders started. Your lower body should maintain its start position as much as possible as you are rotating your upper body 90 degrees to the right and you should work on getting your upper back flat to the target by the top of your backswing.
As your upper body is rotating, you should maintain a straight and extended left arm position, keeping your hands out and away from your body as you move and your left arm should mirror/cover the line of your shoulders at the top of your backswing, allowing your hands to achieve a head high position.
Your wrists should have hinged to create a right angle between your left arm and the golf club shaft and the shaft of the golf club should be pointing parallel, left of the target at the top of you backswing and also horizontal, or just above horizontal, to the ground.
As you make this movement, remember to maintain a very static head position.
Achieving this position at the top of the backswing will allow you to now swing back towards the ball with maximum efficiency in your movement, creating power and speed for you to deliver the club head to the ball with.
If you work on achieving these points in your golf swing, you will strike the ball much more consistently, achieve greater accuracy and the longest shots that you have ever hit.