Most experts assume the book proposal is where a trade nonfiction book begins. I think it begins much earlier. Long before you fill out a proposal template, you can start testing your ideas in public—through articles, talks, podcasts, newsletters, and conversations with readers. Those interactions become a form of research, helping you discover what resonates, what needs refining, and what your book is really about. By the time you write the proposal, you're no longer guessing. You're writing from evidence.