Say you'd like them to stop hoarding so many toys and learn to share. You can start by picking a toy that isn't so important to them and make a goal of sharing. Use simple terms and talk to them about what you're going to do. Write it down and have them help by putting a smiley face or sticker by the goal - this gets them participating and involved in the process. Once the goal is met, have them check it off or put a stamp by it. Then pick another toy that is a bit more important, and repeat the process as needed.
You can use this for setting a good bedtime routine, potty training, helping clean up toys...anything. These charts are a great way to introduce a new skill and get the family focused on creating a positive environment. Just remember to stay structured and consistent.