Two Deadly Words: So What?
You describe the book you are writing to a friend, an agent, maybe a publisher. And they might think - if not say - "so what?" What does that mean?!
It means what is unique about this story? What is the "hook"? What are the stakes? Ultimately it means "why would I read that?"
Be your own critic and ask this question of your book right now: So what? So what a married woman goes to a writer's retreat and is tempted to cheat? Yeah? And - what else? Another story about infidelity or self-discovery is not, so far, sounding very unique, is it?
Think of the So What question as what you think when you are examining the back cover of a book (or reading the book's description online). You know that feeling, right? We only have so much time and money, and we flip through our choices. This one? Or that one? What grabs you at first? Usually the title. Then you dig a little deeper, what's the book about? And you make your decision rather quickly, don't you? Eh - another book about Andalusian horses. What makes this book special? What makes this book worth twenty bucks and eight hours of your time? So what, Andalusian horses.
UNLESS there is something to answer that "so what" question. And that, dear reader and writer, is your hook. "Hook" is a Hollywood term for something about your story that is unique. It's a book about a blind man who trains Andalusian horses during the second world war. Aha - now that has a hook.
Ask yourself, what is the unique hook about your story? What is that "so what" that you can resoundingly answer, as a reader is flipping through choices and has stopped on your book. How is your book different in premise, character, genre or world (the setting) than the next book which is also a YA fantasy book?
This is a question you can both ask when you are mulling over the idea of the book before its written, or that you can ask of it after you've written a draft. So what? How is this book uniquely entertaining? It's crucial to be able to answer this question.