For most business books, the best first step is to get it all out. Dump everything into your word processor. Dictate your book and have it transcribed. That will give you a zero draft, the one before the first draft. Once you’ve got it all out, you’ll know a couple of things.
You’ll know what you’ve got. It’s too easy to fool yourself about what you know and how well you say things. Use this zero draft as a reality check.
You’ll also discover what you don’t have. A zero draft will highlight the gaps in your material so you can plan additional research.
Great writing is rewriting and you can’t rewrite what you haven’t written yet.