Learning and practicing correct posture is an important fundamental to master.  Mastering your posture can be elusive, however, because from one day to the next your body can feel quite different.  You may have slept poorly last night or perhaps you played many days in a row and you are fatigued.  In any case, using a mirror for feedback is one of the proven ways to keep your posture in check.

The best way to see your golf posture to stand side-on to a mirror with a 5-iron.  You are looking for an athletic stance where your knees are flexed, your back is fairly straight, and your pelvis is in a neutral position.  By neutral I mean that your belt buckle is tipped forward so that it is below the level of the back of your belt.  You should not, however, feel like you are sticking your rear end out.  This is faulty instruction.

Once you have taken your athletic stance, grip your 5 iron and address the ball.  Your key check point to be sure that the grip end of the club is pointing approximately at your belt line.  This will help you to find the proper height of your hands at address which will in turn help the club to get started on the right line in the takeaway.

Practice this key check point with a wedge, 5 iron and driver for maximum effectiveness.