At MADRA we usually feed our dogs a relatively high quality dry dog food. They are a bit more expensive, however we find the dogs are healthier and we tend not to have as many problems with them. A good diet can make a big difference for the rest of your dog's life.
You will do well for your dogs if you buy a good quality dry dog food (one without by-products). You can dress it with some meat broth (no salt added), leftover vegetables or lean meat scraps. Dogs with allergies or dry skin can often be helped with an Omega fatty acid supplement.
Just as your dog needs proper nutrition from his food, water is an essential "nutrient" as well. Water keeps the dog's body properly hydrated and promotes normal function of the body's systems. During housebreaking, it is necessary to keep an eye on how much water your dog is drinking. Once he is reliably trained, he should have access to clean fresh water at all times. Make sure that the dog's water bowl is clean and change the water often.