You require your players to do certain things in game situations. These requirements could also be considered expectations. There is one question a coach needs to ask themselves about these expectations:
If you expect it, are you practicing it enough?
One example of an expectation coaches have for their players is to step in and take a charge on defense. Do you actually practice taking a charge? Taking a charge is a part of the game that needs to be drilled so players can feel comfortable stepping in and give up their body for their team.
Another example is diving on the floor for a loose ball. Do you practice this? If you expect your players to do it in a game then it needs to be practiced so it becomes second nature to your players.
A third example is setting and using a screen. Do you practice it? Your players probably know when and where screens are to be set within your offense. Showing your players and drilling your players on how to set and use screens is important for it to carry over into game situations.
Letting your players know they have to do something is one thing, but practicing it and making it part of "what you do" is another. Coaches are always looking to improve their X's and O's. Coaches are always working on helping players with their technique. But are coaches having their players practice the expectations of the coach (like taking a charge or diving on the floor for a loose ball)? Telling your team it is important is one thing, but practicing it and drilling it is going to help your players meet these expectations.
Figure out what is important to you as a coach for your players to do well. Expect that they do it well, but don't forget to give them a chance to practice or drill it in practices so it becomes second nature to them.