Do not hit your dog with a rolled up newspaper for example. It is the tone of your voice and the way you act which tells the dog he or she has done a bad thing. Do not come up behind the dog and surprise it with discipline. This can startle your dog. Make sure you look right at your dog when you correct him or her.
Eye contact is very important.
Do not carry on a conversation with your dog. Dogs do not understand. I have to tell you this everyday. And if you are not yelling or raising your voice, Patches doesn't even know that he has done something wrong. Then let go after a few seconds and wait a few minutes before petting or praising your dog.