"Writing Down the Bones: Freeing the Writer Within" by Natalie Goldberg
These two books are important in the fact that one I discovered at my college library, and the other a used copy at my university bookstore.
"Characters-" revolutionized how I came to the craft.
Before, I thought I was a lesser writer to those who wrote Plot-driven stories rather than Character-driven (which is where I was).
Then, in packing my arms with books to take home - I was taking a Creative Writing course - I read Maren Elwood's classic reference. It broke the book into sections as a textbook, with questions to ask yourself but had a very conversational tone.
Though old-fashion in terms of advice: "Don't write about interracial relationships" (guilty!) "Don't discuss religion" (also guilty) as well as don't use any one other than an All-American guy or girl as your protagonist (Aka White American - I'm Black and have used numerous ethnic groups in my stories...so I've also failed that), the book hasn't failed to teach me how important it is to take your characters seriously, so that they can color the way you tell a story.
Yet, this is the entire point of this reference. You do not need copious amounts of expository.
Goldberg is a student and practitioner of Zen Buddhism, yet, you do not have to be a Buddhist to appreciate the parable-type wit and wisdom she packs in this slim book. It literally changed how I viewed life as a writer and to accept what comes in order to continue your destiny along this path.
In this book, writers can be born, but they can be MADE as well.. and both kinds will know this is WHO they are.