Be clear about your rules. Children should be able to repeat them to you. Explain why the rules are the way they are. Children who understand the why behind a rule will usually live by it. Set an example for your children.
Actions speak louder than words.
Talk about consequences with your children. Ask them what the consequences should be for breaking the rules. When rules are violated, enforce the consequences. Helping your child learn that actions have consequences is important. Remember that children are different.