A big mistake weekend golfers make is taking the club too far to the inside on the backswing. This makes the club "cross the line" and point to the right of the target at the top of the backswing. From here, it takes all kinds of compensations to get the club back on plane and in position to make solid contact.
FIX: SWING A RANGE BUCKET
Stop the mindless hacking, grab your range bucket, and toss about 10 balls in—enough to fill the bottom of the bucket. While holding the bucket (instead of your club) in both hands, make a normal backswing and see if you can get the basket above your right shoulder without spilling any balls. If you snatch the bucket inside too quickly, the balls will start to drop—and as you reach the top, they may hit you in the head.
Practice this drill slowly at first, gradually turning your chest and shoulders away from the target and hinging the bucket upward until you can dump the balls behind your right shoulder and hip. That’s a successful on-plane backswing and will have the club in a better hitting position at the top. From there, move the empty bucket down toward impact, pointing the bottom of the bucket at the ball to groove an on-plane downswing. Repeat this drill several times, then grab a 7-iron and try to re-create the same feeling in your swing, dumping the imaginary bucket of balls over your right shoulder and then pointing the bucket at the ball as you come back down to impact. Your good swings will become a lot more consistent and your ballstriking will improve significantly.