One of the biggest faults for an amateur golfer is not hitting the ground in the correct place when using an iron. As the golf ball is sitting on the grass it must be struck with a descending blow thus resulting in the divot starting after the ball.
There are 2 key points to ensure a downward strike. Firstly during the downswing there must be a move of the right knee towards the target so your weight gets onto your left side. Secondly you must strike the ball with your hands in front of the clubface at impact resulting in that descending blow.
Striking down the ball.
Divot after the ball.
Adam Scott driving his legs forward on the downswing.
Tiger Woods address position compared to impact position. Hands and knees have moved forward to the left resulting in great shaft lean.
These 2 keys will help you hit your irons more solidly.