A big difference between the forward range of motion of the throwing and non-throwing shoulder increases injury risk. Here is a simple test to identify such difference and a stretching exercise to keep the shoulder balanced.
One of the best ways to protect against arm injuries in youth baseball and maximize your child's natural ability is to teach proper pitching mechanics at as early an age as possible. Teaching your child about pitching mechanics doesn't need to be complicated, and it doesn't need to be too technical, but you and your child must be willing to commit enough time to understand the entire process, step by step.