I once attended a talk on ideas for writing books, these are a selection of the methods that seemed most appealing from the talk summed up as briefly as possible.

1. Interviews

Method: Interview an expert then transcribe the conversation and lightly edit for grammar and lulls in conversation.
Tools: Recording software/device, signed speaker release form.

2. Blog to Book

Method: Write a blog post of at least 500 words, include the sub-headings and bullet points – then expand on each point making your subheadings into chapters and the bullet points into sub-sections.
Tools: A fairly popular blog post that has the potential to be expanded.

3. Fictional Mini-Series

Method: Plan the basics of a plot that can be spread without feeling thin with good character development. Publish as you write, aiming for a release every 3 – 5 chapters. Create a brand around the series.
Tools: Authoring / writing tool such as Scrivener.

4. One Question = One Book

(aka – the Quick Guide)
Method: Answer one question and expand on it with examples / case studies. While writing, try to avoid passive voice (e.g. “How to Price my Book” instead of “Pricing my Book”).
Tools: Social media and an authoring tool such as Scrivener.

5. Webinar Method

Method: Schedule and promote a webinar, record and transcribe the webinar and edit appropriately so the content does not reference things the reader cannot see or easily visualise.
Tools: Webinar and screen capture software.

6.  Kindle Singles (Fiction, Poetry, etc.)

Method: Choose a topic and write 5000 – 30,000 words then nominate the self-published book and publish via Kindle Direct Publishing and follow the instructions. Amazon vetts the book and promotes if vetting is passed, only works of fiction are accepted.
Tools: A Book proposal.

7.  Speak It!

Method: Give a talk over a powerpoint, slides will become chapters and bullets subsections. Transcribe the audio or write from scratch.
Tools: Recording device, editing and office software.

8. Compilation / Anthology

Method: Choose a theme, get authors to write a short based on the theme – collate and review/edit submissions then compile into a single book.
Tools: Author manager and a website to promote on.

9. Podcast, Kindle Edition

Method: Start a podcast, transcribe each episode or compile like-topics / shorter episodes together – edit: checking spelling, names, resources. Or heavily edit converting from spoken transcript into a reading friendly book edition.
Tools: iTunes account or podcast creation software than can syndicate to iTunes and recording equipment and software.

10. Crossed Micro-Niche

Method: Write one book, then re-tool the content to fit another similar audience – ensure a disclaimer is contained such as an be found on Janis B Meredith’s Softball Moms Survival Guide).
Tools: Your imagination to come up with a topic that can fit into several niche categories.

The Most Important Thing!

Publish quality writing, always start with the writing then edit, edit and edit again. Find a good cover design, hire a designer on Upwork or Fivr if you’re not visually inclined.

Make sure the interior formatting of the book is logical and easy to navigate, don’t rely on auto-generated content/indexes.

If Amazon publishing, adhere to the terms of service for books and their descriptions. Nothing is going to destroy an online reputation faster than negative reviews.