The ability of dogs and humans to understand each other is astounding, but you can facilitate your dog's training by praising it correctly. A dog understands you largely through simple repetition of positive and negative reinforcement. It's crucial that this reinforcement be consistent, and to associate good behavior with high praise in the dog's mind. If you're consistent, and if you communicate your praise to your dog with your entire body, the results will be apparent in the dog's subsequent behavior.
Instructions
Use a consistent, positive tone. It's up for debate whether a dog can tell the difference between different words, but a cheerful tone communicates a great deal.
Smile. Like your tone of voice, you facial expression and body language all communicate more to the dog than words alone.
Be tactile: Dogs respond to touch as much as sound. The dog will definitely understand the praise better if you scratch it behind the hears or rub its head or belly. If you start off praising the dog verbally and tactilely, then it will associate the two so that when you eventually start to use verbal praise alone, it will have much more meaning for the dog.
Give the dog consistent phrase. Whenever a dog does something right, make sure that it hears praise. If you only scold it when it does something wrong, you won't be giving it good guidance on how to behave.
Praise the dog as soon as it does something good. The associations in its mind will be much stronger if it hears praise immediately after sitting or rolling over. If you praise it after it has performed multiple actions, or if you wait a while to praise it, it won't know what to associate the praise with. When a dog associates consistent praise with good behaviors, and when you properly reprimand the dog for bad behavior, the dog's behavior should also become consistently good.