There are six standard dog personalities and numerous common bad habits. Dog trainers know how different breeds tend to behave. They look for signs of ill health or other reasons for bad behavior. The best training methods use praise and positive reinforcement to train the dogs. Violence is not used.
Trainers try to think like the dog.
Then they look at what they want the dog to do. The training proceeds slowly toward success. Most trainers use a hand leash when training the dogs. Nylon slip collars or leather buckle collars cause less damage to the dog. Advanced training may require months of work.