This mostly applies to long haired dogs but it can all be used with short coats as well. Since I used to raise and show Shih Tzu's I do have more experience than I want with long coats. First do not put a collar or a harness on anymore than you absolutely have to, they break the hair. Do not put them in tee-shirts or sweaters as they wear on the hair. When you bathe the dog use the most gentle shampoo you can find and wash carefully. When you are convinced there is no more soap in the hair, rinse it again. Do not use cream rinses as they weigh the hair down. Do not use a brush on the dog when the hair is wet, use a wide toothed comb. The brush will break wet hair. Brush the hair gently once a day. Feed the best quality nutritionally balanced food you can get. Remember that while coat is important it isn't even half the score on a dog.