We see on tv dog programs that show how quickly a dog turns around from a bad behavior once a personal trainer comes to their home. Some dogs respond positively to training in the hands of a professional but the real training is what the owner learns. The purpose of having a private lesson is to help you master how to handle/train your dog. But once the trainer leaves you with your dog, it is up to you to practice the daily instructions given by the professional. Without practicing with your dog chances are he won’t retain what was taught at the first lesson.
There are tools that some trainers use for walking a dog on a leash, such as a choke or a pinch collar. These can get quicker results, but it is at the expense of the dog. These collars are correction collars and usually used before the dog is given lessons on where on the leash to walk (at your side). When you “correct” a dog before it knows what is expected you break down the relationship creating fear in your dog instead of a happy, willing worker. So when you hire a trainer whether private or in a class situation, go with one that is willing to take the time to show you how to handle your dog and then make sure you practice.