For this drill, take your stance so that your feet are up against the Foot Alignment Bar. The idea is that when your club is parallel to the ground it will be positioned directly over the Alignment Bar (as shown).
When your club is parallel to the ground, your wrists should be slightly hinged, not cupped or bowed, and the toe of your club should be pointing up in the air (or a fraction closed). From this pre-set position, simply turn your shoulders through 90-degrees to the top of your backswing. Then pause and swing slowly down and through. Practise this movement until it becomes habitual.