Without thinking extensively or sweating much, write out your first pass of a list of things you will cover to support your big idea: how you will approach the idea, what will your reader need to know to see the problem, what will they need to know to answer the problem.
A healthy list will probably have about 8-12 topics. Your list will depend on the scope of the problem you are addressing and the detail you will provide.
It may be your first attempt at an outline; the topics and order of topics will evolve as you write the book. You may decide some material may be better suited attached to a different sub-topic, or you notice some material is off-topic (which means you can save it for your next book). The goal is to have a clear and concise book that gives your reader a feeling of empowerment and agency. For now, you’re just testing the flow of ideas, their relevance in support of the big picture, and seeing everything is developing toward clarity and results.
Once your information finds a more permanent order in the line-up, you should aim to have approximately 8-12 chapters. Each one of those points in your rough outline becomes its chapter.
Now you can start adding more material and detail to the topics in the outline, adding sub-topics and essential pieces of evidence in your arguments. The more detail you add, the easier the leap to writing the manuscript becomes. You will have a detailed map of what you will write about, its order and everything you need to include in your book. You can focus on the writing of the manuscript and not worry about planning, organizing or research. It is already in your outline.
If something occurs to you in the writing that requires a change in the outline, change the outline. The outline is not written in stone.
If you need help with your outline, Ardith can help you put one together.