All praise is good, but praise specially tailored to connect with the dog's way of reacting is ten times as effective. Here are some tips to follow:
1. Use the right tone of voice. Dogs communicate with one another through sounds easily duplicated by humans. If you're angry with your dog, for example, dropping your voice to a low rumble closely approximates the growling of a dog. For praise, use a sweet, high-pitched crooning voice: "Goooooooood, doooogggg!"
2. Tailor your petting style to your dog. Some dogs go crazy when petted; others hardly notice. Use a little chest pat or scratch for those who tend to be overly enthusiastic, and be a little more boisterous for the ones who really warm to being jollied. Don't let the dog use petting as an excuse to go crazy - lighten up on the pats, but don't correct him - and let your voice do most of the praising.
3. Smile. Dogs understand many of our facial expressions because they use similar ones to communicate with each other. A smiling face is understood in both species, but if you really want to get through, make the smile as wide open as you can. You're trying to approximate that big panting grin a happy dog has.