HOW TO ADJUST YOUR STANCE
Generally, the less lofted the club, the shallower the angle of attack should be; the more lofted the club, the more descending the angle should be.
With the driver and fairway woods, your stance should be fairly wide and square to support the long, sweeping swing required to hit these clubs. But as you go through the bag, to the long, middle and short irons, you should progressively narrow and open your stance to set up an increasingly descending downswing.
You'll find that positioning your feet in relation to the length of the shaft—open and narrow with short clubs; wide and more square with longer ones—is easy to get used to.
Opening the stance for short clubs also pre-sets the body pivot through impact. You don't need power with these clubs, but you do need control.
Tip courtesy of Arnold Palmer in Golf Digest.