Before we get into how to choose the right dog shampoo, let's take a look at how to use dog shampoo to begin with. Mix about 1-2 tablespoons of shampoo with enough water to make a thick paste. Apply the mixture to your dog's coat using a small amount of water. Rinse thoroughly. Repeat steps two and three until the entire coat has been cleaned. While this method works well, it does not provide as much care as you would like. This is where choosing the right dog shampoo becomes crucial.