As a teacher, I've been on a journey my whole 12-year career and I'm finding parenting is a similar type of journey.
I am reading the book right now and have already tried some things on my 3-1/2 year old daughter this weekend. I have quite a strong-willed child who has hit the terrible 3's. (The 2's were so much easier for my husband and me.) I've always used choices with her for discipline, which makes life simpler, but I didn't use contingencies—just, "If you don't clean up then you can't go to the park." Saying, "If you clean up, you can go to the park," sounds so much better and works much faster with her. But I have to stop and think a great deal to decide how I'm going to phrase things.
Just now as she sat on the floor with our pit bull—he just wants to be near her but she treats him as a sibling—he's touching me, he's in my way, etc. She started having a fit about him. I just told her very nonchalantly that if you leave him alone you can stay in your spot. (She had a bed tray with her pizza on it watching her favorite show.) She said nothing more and even cradled his head and has been fine ever since. Before we would have gotten on her about being nice to him, stop pushing him away, etc.
I told her earlier when she cleaned up her toys, we could go to the park. She's never moved so fast. It's amazing!
Additional discipline information my be helpful at the impulse control link.