A hunter's shotgun stance is similar to that of a boxer - in a standing position with feet apart at shoulder width. For right-eye dominant shooters, the left leg will be slightly forward and the left foot pointed toward the anticipated target. For left-eye dominant shooters, the right leg will be slightly forward and the right foot will be turned slightly. The hunter bends forward at the waist. The forward leg of the hunter is bent slightly, not locked.
The hunter raises the shotgun to the cheek under the dominant eye first and then back to the shoulder. The positioning of the shotgun on the cheek is critical. If the shotgun is not placed correctly against the cheek, the shot will either be high or low.
A general rule to follow is that the stock be held comfortably - not too tight or too loose - against the cheek, just under the cheekbone. The hunter's head has to be held straight, not canted to the left or right.
Have someone check the fit before you purchase a shotgun. Some shotguns have shims or adjustable stocks to help with this alignment.