When I run my basketball shooting clinics, I always stress consistency and repetition when shooting the basketball.  Each time we start a session, we start under the basket with our form shooting drills.  For my guys, each form shooting session starts no more than 3 feet from the basket and takes the player through the proper balance, footwork, and arm and hand alignment that is necessary to build a consistent jump shot.  My players start with one hand form shooting, then they add the guide hand, and then finally, they do a simple step-in drill.  With the step in drill, players are encouraged to step with their left foot first if they are right handed and their right foot first if they are left handed.  In each one of these drills, the player must have good knee bend to promote lift on their jumpers.  Players are also encouraged to swish every shot and leave their follow through.  This promotes shooting the ball with arc and also ensures that if they try to swish it, if they are a little off the ball still has a chance of going in the basket.  Finally,  each player must focus on repeating the exact same motion each time he shoots the ball.  Repetition is one of the most important factors to building a great jump shot and by building this type of consistency in our form shooting drills it will ensure that we have the same type of consistency in our more advanced drills and most importantly, games.  Below is a video that NBA pro Ray Allen put together that discusses the importance of repetition when shooting a jump shot.  He also provides a few good shooting drills that will help to build a consistent jumper.