I have most kids that I coach go from the stretch position rather than using a wind-up. It helps you stay balanced and is the position you will use when the game is on the line. If you have to go from the stretch with a runner on base, why not just do it all the time?
Stand with your feet about shoulder width apart and your weight distributed about 60/40 % in favor of your back leg. This will help you deliver the ball to the plate quickly and not allow base runners to get such a big jump. The outside of your throwing side foot should be lined up with the front edge of the pitching rubber. Your glove side shoulder should be pointed toward home plate. The ball is in your hand, which is in your glove, and rested comfortably between your chest and waist.