A Quarterback has to make positive decisions. He is ultimately responsible for protecting the football. A phrase I learned very early in my coaching career is "before you can ever win, you must prevent losing." In today's world, and in everyday language, that simply means the team with the fewest number of turnovers wins. Thus, the QB can not turn the football over. I have always preached any throw a QB makes, of 20 yards or less, must be thrown below the receiver's chin. The shoulders should be at an angle where the left one is slightly lower than the right, for a right handed thrower. The idea is that if the ball is inaccurate it will fall incomplete. A high throw can be tipped and intercepted, that must be prevented. To create a picture in a QB's mind as to the posture he should have when executing this type of throw I have always told this story.
Billy has been working out on a hot summer's day and he walks into the kitchen to get a glass of water. As he is standing at the sink his younger brother, Tommy, who is a bit of a pain in the butt, starts to give him a hard time. Billy's parents have always told him to not get aggravated by Tommy but on this hot day Billy is struggling to hold his composure so he decides to walk away. As he goes up the stairs, in order to retreat to his room, Tommy is still giving him a hard time. Once he reaches the top of the stairs Billy losses it, picks up a football, turns and throws the ball at Tommy yelling, "shut up you little brat." Think of the picture created. Billy is at the top of the stairs, throwing the ball downhill at his intended receiver, Tommy. That is the way every throw of 20 yards or less should be executed, with a downhill angle to the thrower's body and shoulders.
Protect the ball everytime you throw it!!