You must collapse the defense (post entry, penetration, offensive rebounding) versus superior teams. You can't win by just shooting 3's. Those that play closest to the rim, win games.
Your players must be able to read and react (speed reading). Teach less for quicker reaction.
Bad spacing leads to turnovers, don't allow your players to turn the ball over.
Angles of passing are important. Don't throw passes across your body, no skip passes in transition, not passes on a straight plane.
Most important decision you have to make with your offense is whether you are going to use an open or closed post.
When you don't have the ball you need to make space for driving lines.
Keep records on all shooting drills and make them competitive.
Swing into your shot rather than being squared up. Heel-toe for inertia or ball in the air, feet in the air.