Give limited choices. You can have milk or juice, but you can't have soda. Too many rules will be hard for them to remember. Remind children of the rules. Once is not enough.
Children are more cooperative when they help set the rules.
When you get angry, find a way to help yourself calm down so that you do not do or say something you will be sorry for later. Take a walk. Go to another room. Listen to music. Take some deep breaths.