Teaching your puppy right so it grows up to be a well adjusted dog is just as important as giving it food and shelter. There could be no one else it would learn behavior from but you. You are ultimately responsible when it comes to developing good habits and attitudes to your dog. There are certain behaviors that your dog must learn so it can live in harmony with the rest of the household and your neighborhood. There are only a few basic ideas behind how you should train your dogs and there is plenty of literature on DIY dog training.

The most common way a dog owner would train the dog is to keep it company and let it do whatever it wants as long as the dog owner isn't bothered by it. This is sadly not enough and the owner is taking on a very passive position. The dog must realize that the owner can assert his authority and assume responsibility so it listens to him. Many owners tend to think that it's needless especially when they have small dogs.
Even small dogs need to be taught some manners and often enough, the small ones are nasty and would nip at a child. You can't let the dog lead you. It should be following your cue, although not all the time. You should be the one dictating which behavior is appropriate in what situation. To do this, you can't just let your dog be around other people or animals when it hasn't learned how to behave well.

What dog trainers usually do is encourage the dog to behave well with the use of praises and treats. Giving adequate praise will certainly tell the dog your approval of its behavior and lets it know how to behave in order to please you. You shouldn't go overboard with the praises especially when you are still in a training session. Focus on the training itself and don't send mixed signals to your dog that it could be time to play.

Giving treats is a classic and works pretty well with animals that exert a lot of energy doing tricks such as seals and dolphins but you're only teaching a dog to sit or behave a certain way around people or other dogs. It may not have a voracious enough appetite to find the treats rewarding especially when you're training it after dinner.

To get the best results in training your dogs, you have to let the dog know that you are the master. Dogs have an innate sense of social ordering. Once you are considered the top dog, it will follow you better. You should be able to give verbal or non-verbal commands and make your dog comply. To do this, it must be clear to your dog that you are the one that determines its welfare. You are the one granting it privileges in the house.