Show off with your sample chapters.
It’s easy to think of a book proposal as entirely separate from your book manuscript. Truth is, your book proposal must include a solid chunk of your manuscript—in the form of sample chapters. Agents and editors want to see sample chapters that demonstrate your ability to write a compelling, commercially successful book. Even if you have a popular podcast, or you write regularly on a specific topic for a respected media outlet, they need to see you can sustain your story, arg