As a coach, one of your major responsibilities is provide your team with as many advantages as you can. You design your practices and drills to work on the things that you believe will help your team succeed and win. (Learn how to build a better young athlete.)
Your best chance at accomplishing this happens before a single player touches the ball. Before you implement a basketball system, you need to look hard at your team and decide what will work best. If you have a dominant big man, you might install an offensive system that feeds the post and have your other guys crash the boards instead of shooting a ton of threes. On the defensive end, if you have tall players who struggle to keep smaller offensive players in front of them, you might want to run a 1-3-1 or 2-3 zone.
College and professional coaches have an advantage, because they can recruit/sign players for the system they already prefer. But high school and small college coaches need to be flexible and readjust their system, pretty much every year, to suit the talent they have available. Don't be too stubborn to make adjustments to your style of play. This is where good coaches separate themselves, because they're able to win in different ways.
Once you have decided on a system, be willing to stick with it. This doesn't mean you should never make changes during the season if something is not working; but you should trust the process. If you flip-flop back and forth between multiple strategies/systems, you're only going to hurt your team. Don't get frustrated. Treat it as an ongoing process and aim to get better at it on a daily basis.
Take the time to teach your players the system and how to use it the right way. As a coach, you are thinking on a different level than your players, especially if the system is new to them. It takes time, so be patient. At the beginning of the year, do your best to make sure your players understand the system—whether by watching film (tips on how to) or diagraming plays. It may be time consuming at first, but it will pay off in the long run.
After you've taught your players how everything works and why they are doing it, hold them accountable. If you let them get away with setting lazy screens or not boxing out, they'll continue to do it all season long. It takes five players working together as a unit to be successful on the court. Be consistent and fair with your players, but let them know they will be held accountable.