I find an area where there just doesn't appear to be any really great "you only need one and this is it" books and I write one.
But, here's a book I won't have to write: Clicking with Your Dog by Peggy Tillman. This is the greatest dog training book I have ever read (out of a large pile over past 22 years of dog training). There are a few that I like and many that I do not – but this is "the one". It is a pure clicker training book that is uniquely easy to read and follow. I have never seen another dog training book anything like it. Having just finished it all I can think about is what a great dog I will have by next year and how much money I have wasted on other books.
And, until now, like with all of my serious hobbies, I expected to write my own "Blue Hair Bob's Getting Started Right with Dog Training" book – but that would be a waste of energy. If you want to train your dog use a clicker; if you want to clicker train your dog start with this book.