Autism and positive reinforcement
One of the hallmark symptoms of autism spectrum disorder is having issues with facial cue recognition. Children on the spectrum often need reassurance that your tone of voice or reactions don't mean you are mad at them. Keeping this in mind, they usually respond very well to positive tone of voice and actions. They are less likely to become anxious if you interact with them in a positive manner which means less likelihood of negative behavior on their part.
Now, that's not to say consequences don't have their place, they do. In fact, it is imperative that you help them learn that their actions do have consequences. That said, remind them that both good and not so good behavior has consequences through positive reinforcement when possible.