There are lots of strategies that you can use to encourage better behavior in kids. The challenge with most systems is sticking with them and consistency. Another problem is that once you’ve encouraged a specific behavior, now what? Try this strategy that uses marbles (or chips or anything like them) to promote a variety of behaviors on a variable schedule.
More Resources
It’s Magic: Parenting Tricks for Changing Behavior
Top Reasons Why Kids Misbehave