If you’ve been trying to figure out how to choose a topic for your nonfiction book, you’re probably in one of two places. Either you have several ideas and can’t decide which one to write first, or you have one big subject you care about and you’re not sure how to shape it into a single book. Both are really common, and both are completely workable.

I’ve been coaching first-time nonfiction authors for over 17 years, and choosing a topic is one of the conversations that comes up most often in my sessions. In this post, I’ll walk you through the steps I use to help authors narrow things down, so you can choose a topic you’ll enjoy living with for a while and that readers will be glad to find.

If you already have one idea and you’re mostly wondering whether it’s strong enough, my post Is My Book Idea Good Enough? How to Know You’re Ready to Write It is a great fit for where you are. This post is about the step just before that, which is deciding what your book will be about in the first place.

Why Your Topic Shapes Everything Else

Your topic affects almost every decision that comes after it. It shapes your outline, the reader you’re writing for, how you’ll describe the book, and even where it will sit on Amazon. When a topic is very broad, the chapters can start to wander, and I’ve seen a lot of authors lose momentum partway through because the book kept trying to cover a little bit of everything.

When the topic is focused, things get easier. Your outline comes together more naturally, you know what belongs in the book and what doesn’t, and it becomes much simpler to explain your book to someone in a sentence or two. So taking a little extra time here really pays off later.

Step 1: Write Down Every Idea You Have

Start by getting everything out of your head and onto paper. Don’t judge the ideas yet, and don’t worry about whether they’re “book-sized.” Just list them.

If you’re not sure where to look, here are a few good places to start:

• Questions people ask you again and again
• Advice you find yourself repeating to friends, clients, or coworkers
• Something you’ve lived through and learned from
• Skills or expertise you’ve built over years of work
• A topic you keep reading about because you can’t get enough of it

You may end up with three ideas or twenty. Either way is fine. The point is to see all of your options in one place.

Step 2: Notice the Idea You Keep Coming Back To

Now read through your list slowly and pay attention to how you feel about each idea. Is there one you keep circling back to, or one that makes you want to start writing right now?

That energy matters more than people expect. For many first-time authors, writing a nonfiction book takes around a year, so you’ll be spending a lot of time with this topic. A good question to ask yourself is, “Which of these would I still be excited to talk about a year from now?” Circle your top two or three and set the rest aside for now.

Step 3: Picture One Specific Reader for Each Idea

For each idea you circled, try to picture one real person who would pick up that book. Not “anyone who wants to improve their life,” but one person in one specific situation. What are they struggling with? What would they hope to find inside your book?

If you can picture that reader clearly, that’s a great sign. If an idea leaves you unsure who it’s for, it may simply need a little more time to take shape. That’s okay, and it doesn’t mean the idea is a bad one. It just may not be the one to write first.

Step 4: Narrow a Big Subject Into One Clear Promise

This is the step where a lot of topics really come into focus. If your idea is something broad like “health,” “leadership,” or “my life,” try narrowing it down to a single promise you’re making to your reader.

Here’s an example of what that can look like:

• Broad: Health
• Narrower: Staying active as you get older
• Focused: How adults over 60 can rebuild strength and confidence after a hip replacement

The focused version tells you exactly who the book is for and what it will help them do. That clarity makes everything else easier, from your chapter list to your book description.

This is also a good time to think about what kind of nonfiction book you’re writing. A memoir, a self-help book, and a how-to guide can all come from the same experience, but each one makes a different promise to the reader. This is something I help authors sort out often. A few of my Pick My Brain clients came to me unsure whether their book was a memoir or a self-help book, and getting clear on that changed how they approached the whole project. If you’re leaning one way, my guides on how to write a self-help book and choosing memoir theme ideas can help you think it through.

Step 5: See What Already Exists and Where Your Book Fits

Once you have a focused topic, take some time to look at books that are already out there on the subject. Search for your topic on Amazon and browse the results. Read some of the three-star reviews in particular, because readers often explain exactly what they wished a book had covered.

Please don’t be discouraged if you find other books on your topic. That’s usually a good sign, because it means readers are interested. What you’re looking for is the angle that’s missing, or the reader who hasn’t been served well yet. Jane Friedman makes a helpful point in her article on how nonfiction writers can find their niche: no matter how many books exist on a topic, there’s usually some important facet that hasn’t been covered thoroughly or well. Your experience and your perspective are often what fill that gap.

A Simple Way to Choose Between Your Final Ideas

If you’re still torn between two or three ideas, try answering these questions for each one. You can jot your answers in a notebook or a simple document.

1. Which idea am I most excited to write about?
2. Which reader can I picture most clearly?
3. Which idea can I explain in one sentence?
4. Which one do I know well enough to write about, or feel ready to research?
5. Which idea fits best with my goals, whether that’s growing a business, sharing a story with family, or helping people going through what I went through?

Usually one idea starts to rise to the top once you see your answers side by side. And the ideas you don’t choose aren’t lost. Keep them in a file, because many of my clients have gone on to write a second book, and those saved ideas often become the starting point.

If you’d like help deciding: Sometimes talking it through with someone who has walked many authors through this decision makes all the difference. One author who came to me with several book ideas and couldn’t decide which to write first told me afterward, “You helped me to clarify my ideas, sequence my next steps, and feel really good about the process.” If you’d like that kind of clarity, a 30-minute session is a great place to start.

Book a Pick My Brain Session

What to Do Once You’ve Chosen Your Topic

Once you’ve chosen your topic, you’re ready for the next steps. First, run your idea through the readiness checks in Is My Book Idea Good Enough? so you feel confident moving forward. Then turn your topic into a simple outline. My step-by-step guide on how to outline a nonfiction book walks you through that, including which structure fits memoir, self-help, and how-to books.

If you’d like to see the whole process from topic to published book, my complete beginner’s guide on how to write a nonfiction book lays out every step in order.

Grab the Free Author Checklist

Before you start writing, it helps to make sure you have the essentials covered. My free Author Checklist walks you through what to have in place before you start writing your nonfiction book, so nothing important gets missed.

Download the Free Author Checklist

How many book ideas are you choosing between right now? Tell me about them in the comments. I read every one, and I’d be glad to help you think it through.