Look for the Zebra
There is an old saying in regard to looking for the obvious, "If you hear hoof steps behind you, look for a horse." I am telling you that when it comes to team shooting percentage look for a Zebra. There are many aspects that make up team shooting percentage. The common perception is that the only aspect involved is getting a player to make a shot. That might be the least important aspect.
First you have to evaluate where you are making shots and where you are missing them. Without exception, teams that shoot a good percentage consistently take a lot of layups. Whether it be an interior oriented offense with a big man, a backdoor oriented offense, a team that runs in transition or a team that creates easy baskets with its defense, teams that shoot for a good percentage take layups. Does your team take enough layups?
Next, evaluate who is shooting. It is simple logic that the players that shoot the best should take the most shots. However, that really is not as simple as it seems. You have to take your philosophy into account. You may have a player who shoots a low percentage because he shoots a lot of 3's. That will definitely lower your overall percentage. You have to evaluate if that is what you want. If so, you have to live with it. But, offense is not an equal opportunity program. Just because one player can take a lot of a particular shot doesn't mean that everyone can do it as well. Prove you can make it in practice before you can take it in a game.
Be more definite in your role definite. There are shooters and there are non-shooters. Allow your shooters to shoot and teach your non-shooters value passing.
A non-shooter may become a shooter if he takes different shots. Evaluate whether you have a player who will improve by limiting his range, playing more on a certain side of the floor, etc. Are you running the right offense for them? Nothing is going to be right for everyone so you have to make decisions as to what is better for your team as a whole.
I don't what to make it seem like shooting practice is not important because it is. Repetition breeds confidence and confidence is the single most important fundamental of shooting.
When you have shooting practice, it should not be just repetition. Your practice should be heavy on technique and timing. Use pieces of your offense as shooting drills. Familiarize your team with when and where their shots are going to come from. It will also be easier to teach them how to get their shots and how to get shots for others.
It is important to realize that if you play and if you shoot, you are going to miss shots. The only way not to miss shots is not to take them. As a coach, if you constantly harp on missed shots, it is going to get worse. Teach your players to accept misses as the cost of doing business. There are going to be some expenses but don't let that get in the way of your profit. Continue to encourage your players to take shots they can make and live with the misses. If they are taking shots they can't make, that is another story. As long as the shot selection is good, free them up mentally by living with the results.
To improve your team's shooting percentage the keys are more layups and better shot selection. Hopefully you can effect those changes in practice and your game performance will improve to a level that exceeds your expectations.