Having students come up with their own rules for the classroom is much more rewarding because students have ownership. If students own it, then they are more likely to follow them. Of course I am allowed to have input, but mainly I turn the words into positives rather than starting with 'don't'. If we don't do something, what do we do instead?
I record their rules on our interactive whiteboard using a wood background. Then each child is given a leaf to decorate with their name for our tree-ty. This is how they sign the treaty. It is a great visual to refer back to when rules are not being followed.