From what I understand about Petco, what they offer are mainly positive reinforcement based training classes while also sponsoring Cesar's show.
I think positive reinforcement based training (not "positive only/purely positive/truly dog friendly") methods paired with Cesar's social philosophies are a great combination, which I also use all of the time. It's mainly combining the teaching of skills, manners, and social boundaries.
If you feel comfortable with it, you can use a lot of Cesar's philosophies to teach owners how to project confidence and calm without even touching the dog. This is a great place to start for a novice, IMO. Most of the shows contain a good portion of working on the owners, anyway. I encourage folks to watch the show and work on themselves, first.
Unless you, the company you work for, or an organization you belong to operate under a strict and narrow belief system which prevents you from simple concepts like saying "no", setting boundaries, giving the dog "a look", a body block, etc...you should be able to incorporate the basic philosophies and the non-physical corrections, boundaries, and redirections as a form of social communication.
The "no touch, no talk, no eye-contact" CM mantra is a very useful concept which can be used to put a dog at ease and to project calm, leadership.
Keeping anger and frustration out of the human/dog interactions is another great tip.
Getting your dog out for a daily walk is also a good recommendation for any human or dog who is able.
Mmmm, philosophy fruit salad.
"Great spirits have always encountered violent opposition from mediocre minds" Albert Einstein
"There's a fine line between fishing and standing on the bank looking stupid"