Giving treats as rewards is a great way of training dogs!
(You knew that, right? :)
Let's look at these treats in a little more detail. Because exactly *how* you give the treats will have an ENORMOUS effect on the final result of your training. "Reward placement" as a training technique is covered in detail in both Intermediate obedience class, and the Give a Dog a Job program, but here are some highlights for everybody.
When you give your dog its treat reward, how do you dispense it? Do you pop it into your dog's mouth? Drop it on the ground for him to pick up? Throw it up into the air for a game of catch? Toss it into a pile of leaves for a game of find it? Any of these are good methods, but if you think critically about which specific treat delivery you use, at which specific time, your training will improve by leaps and bounds!
A GOOD GUIDELINE: Passive treats for passive behaviors; Active treats for active behaviors.
Let's look at "stay" -- the "sit-stay" and the "down-stay."
For pet dogs and most service dogs, "stay" is a passive behavior. To train "stay" to these guys, it's cue "stay," wait 1 second, "Yes!" and return to dog/pop treat into mouth. The dog does not have to do anything or get up to get its reward. It may as well just settle calmly into its stay, and that's exactly what it does!
Sports and competition dogs, on the other hand, need to learn an "active" stay. This ensures that they are ready on a moments notice to spring into action! (You definitely don't want your agility dog falling asleep on its start-line stay.) And a Rally dog needs to be up and heeling briskly on a moment's notice. For these dogs, you still cue "stay" and mark "Yes!" for success, but instead of returning and handing the treat, you throw it! (Which direction you throw it should also be thought out. If your dog tends to creep forward, you'd throw it behind the dog. If it tends to settle into a down position from a sit, or to a hip-down instead of the fancy Sphinx down, you'd throw it up. If it tends to lag into heel, throw it forward.) The thrown treat will help "explode" the dog out of stay, then you will have plenty of dog for your agility or rally course.
"Stay" is just one example of how the same food treat can be used differently to achieve different styles. Reward placement is one of my favorite topics of dog training; I find it fascinating!