Make decisions. In the movie Wonder Boys, Professor Grady Tripp (Michael Douglas) has difficulty making decisions in his life, and this translates to the book that he is writing, which goes on and on in increasing detail, but doesn’t go anywhere. As Hannah (Katie Holmes) tells him when she gets a sneak peek: “You seem not to have made any decisions… At all.”
When you’re writing your book — whether it’s fiction or nonfiction — you need to be able to make choices about the things you are going to include and the things you’re going to leave out. Even in the longest, most complex works, authors have had to make these kinds of decisions — don’t let them fool you. So decide whether your main character should be a plumber or a security guard. Decide whether he should live in Wyoming or Massachusetts. Because reading about a plumber who moonlights as a security guard on the weekends and lives in Wyoming during the summer and Massachusetts in the winter may sound like a happy solution to you — and perhaps it is, in some cases — but more likely the book will come across as diluted, lacking focus and weak. As will its author.