Campbell offered a classic definition of mythic structure in storytelling. The narrator, the hero, starts a quest and faces challenges that change him or her by the end. It's the structure you see in so many films, books, and classic fairytales. Most movies out of Hollywood follow this structure.
In the big W, there are three defined sections, or three acts. Each gives the story a certain kind of movement, up or down. The sequence creates a W, falling action and rising action, back and forth.
Since a book is a big project, this template can make order out of your pages of chaos. First question to ask yourself: can you divide your story into a rough beginning, middle, and end? Good.
Next questions: Does the beginning provide a challenge, an initial crisis (also called a "triggering" event because it's similar to pulling the trigger on a gun--it must propel change).
In the middle, do events get more complex? Maybe the initial crisis becomes bigger. Maybe more a problem isn't solved as easily as we expected. Do positive events change someone's life in some way, causing their own problems?
Finally, is there change by the end? Do things resolve at all? What is different about your hero by the final page?
These are the basic elements of the big W. Use its template to check your book's structure. You may find some pieces missing! If so, read on.
Act One: Set Up a Strong Beginning
Ask yourself, Is the dilemma presented immediately and clearly? Is it big enough to propel the entire book? Remember that a triggering event should be an externalized action without which the story would not happen.
Act two, or a book's middle, is a tricky part. It's easy to get sleepy here. How many books have you abandoned as a reader, after a great start, because of the slow down? The big W helps you avoid that.
I like to call act two the arena of "new complications." It should make your hero's journey a lot more complex. Does it?
Act Three: Finishing with a Surprise
Act three is like a big exhale of tension. It delivers a new level of clarity about the story or subject. Your characters might realize how much they have grown, and how overcoming all those dilemmas earned them their insights.