Always enter the class Genki and in a good mood even if you just broke up with your girlfriend.
Try to be as much energetic as you can be ,use a lot of jesters and raise or lower your tone according to your content.
always have a second plan for your lesson ,just in case the kids are in a different mood.
Try to explain the meaning of each theme or game or rules for the kids to understand ,make sure they all get the point otherwise you are just wasting your time.