I had a friend who had problems learning to inhale without choking. So I put ice cubes in the bong water. That helped him a lot. Another way to help him if he has trouble drawing smoke tell him to draw it into his mouth, then slowly inhale the smoke with his lips parted a fraction. In this way as he's pulling the smoke down his throat some fresh air also gets pulled in at the same time. Eventually he'll get the hang of it. If all else fails, blaze up in a car with the windows closed. He'll get the buzz second hand, but he'll get it.