Fear spawns fear. Love attracts love. A child who is treated with understanding, will learn to extend understanding to others. If you want the children to be kind and considerate to one another, be kind and considerate to them. If you walk around smiling, make sure you are smiling from your heart.
Children always detect hypocrisy.
Only when you are genuine, can you transfer the value of smiling, peace, joy and happiness. No matter what you teach, if you have these qualities, you will touch children with your words. You will transfer values even without talking about them. Children will receive them, gaining an enormous amount from you. I had a friend who taught in a school in a very rough area it was well known that many teachers refused to teach there.