I have never seen a list of positive words in this context. My idea would be whenever you get ready to say, "don't do this" , "stop that" figure out a way to say it that the child will know what to do. Instead of "don't climb on that", say "feet on the floor". Instead of "stop throwing the blocks", say "blocks are for building". It is really a matter of training yourself. It is worth the effort, the climate in the classroom changes dramatically.