1. Start off firm and ease up from there if appropriate. Do not be nicey nice. 2. Get the class TA (if you are lucky enough to have one) on board. Ask them to help with behaviour. They are often more likely to listen to them because they know them. 3. Say at the start that you are looking forward to leaving Mr or Mrs x a good letter to say what a good day you've had with the class. 4. Don't let any little thing go otherwise it will escalate. 5. Be the boss. 'No you can't go to the toilet now but you can go in a few minutes when I have finished this!'