Having a correct golf setup with the irons is the first step to hitting better and more consistent golf shots. Ball position for the irons should be slightly forward of the center of the stance. The stance width should be about shoulder width.
You want the arms to hang down extended in the golf setup but you don't want to lock your elbows. The elbows should be close together and relaxed. The rest of the arms should have medium tension or be slightly tighter than medium.
The hands should be slightly ahead of the ball about one inch and the shaft of the club should lean forward or towards the target. Forward shaft lean in the setup is one of the most important factors to be able to hit down and compress the ball correctly. You want the club to be at the same angle through impact as it was in the setup position.
To hit the irons correctly, it's important to hit the ball on the way down. This doesn't mean you want to chop down on the ball. It simply means the club shaft should be leaning forward and the hands should be slightly ahead of the ball at impact.
If the club were leaning back and you were hitting the ball on the way up, you'll hit a lot of fat and thin shots. The irons are designed to hit the ball on the way down so that the angle or loft of the club is what gets the ball up in the air. A golfer who tries to help the ball up and hit up on it will not use the loft of the club correctly and can't hit it in the sweet spot or middle of the clubface.
A common problem in the swing is flipping the wrists too much through impact. This causes the shaft to lean back. Leaning the shaft forward in the setup will actually help to minimize any wrist flip through impact. The more a golfer sets up with their hands too far back in the setup the more they will swing through with the shaft leaning back.
It doesn't hurt to exaggerate the forward shaft lean in the golf setup if you are having trouble making good contact with the ball. A golfer can get away with a little too much forward shaft lean but if the shaft is leaning back it can be tough to make good contact. Getting the feel of hitting down on the ball will really help you hit your irons better and eliminate many swing faults.