Winifred Strickland said “do not be ashamed to praise your dog in public”. She wrote the book Expert Obedience Training for Dogs. She said not to use food as a reward that the dog will think more of the food than of the handler. I am not sure about that, from what I have seen even dogs that have been abused continue to like their owner, it is the pack instinct. I believe in the method of using a high profile reward such as a treat along with praise, then wean the dog off the treat and just use praise. One thing I learned early on about praise is just patting the dog on the head with an “atta boy” doesn’t work too well. When I was learning to train dogs for search and rescue, we used three minutes of continuous praise, rubbing and petting with a high squeaky voice. That was the way we praised the dogs when they found a subject. It works and it doesn’t work so well when you don’t act like a silly fool for at least three minutes. This is one I am not certain about, but I still do it.