First of all, the players must be effective, not impressive!
Regardless of the offensive system or the position they are playing, the players must be able to catch and shoot, shoot of the dribble, be able to pass the ball from one side of the court to the other - even the post players. They must attack the defensive player at the correct angle, pass the ball under pressure, as well be able to get open.
Trying to become elite at anything takes a lot of sacrifices.
If you want to become the top 1% in the basketball world be prepared to grind like nobody you know.
If you're the hardest working player on your team you should probably find a new team...
FUNDAMENTALS! The word of the day is fundamentals.
It's extremely frustrating when the kids you're working with know what's "split step", or "double drag between the legs"... but don't know what is weak or strong side, or don't know how to stop properly and take the first step properly.