Where are you looking when you shoot the basketball?
Your eyes should be on the back of the rim at all times. When you look at the back of the rim you are actually looking into the basket. Many people teach players to aim at the front of the rim; but if you do you actually having to overshoot your mark to make a successful basket.
The ball should lay on the upper part of the hand, not the palm. There should be some space between the hand and the ball. This should feel soft. Proper fingertip control is extremely important in the art of basketball.
Where are you in relation to the rim. Are you feet aligned up with themselves and the rim? What about your hips? Are you over extended? abs engaged?
It is extremely important to be aware of where you are in relationship with your opponent(s) and the rim at all times. But more importantly you must feel comfortable in your position. The simpler the shot, the least amount of unnecessary motion, the better the chance for consistency of routine.
Release and follow-through
Smooth like water. The feeling of wet; as we would call it out as kids whenever the ball would fall perfectly in the hoop. Your release should always be smooth and fluid, never jerky. When a movement is jerky it has a tendency to move faster. When a ball travels fast it has less chance to work for you.
The ball should roll off the upper part of the hand and then slide off the fingertips easily.
If your shot rolls in and out of the basket, that tells you shot is likely too flat, it needs more arch. A shot falling from a higher point will hang more softly on the rim.
NEVER CONCENTRATE ON THE FLIGHT OF THE BALL
Most good shooters know they are going to make the shot. ALWAYS walk to the line, spot up, or create a jumper with confidence in knowing you will make the shot