Guide
What book should I write?
Most unfinished books were doomed at the subject, not the writing. The ones that get finished and read share a shape: narrow enough to cover completely, close enough to something you have actually done, and aimed at a group of people who already gather somewhere.
Short answer
Pick the intersection of three things: something you have done or survived, something a specific group of people needs, and something narrow enough to cover in 30,000 words. Test it by naming the exact place your reader already gathers and writing the subtitle before the book. If you cannot name the place or write the subtitle, the idea is not ready.
The three circles
A book worth writing sits where three things overlap. Miss any one and the project tends to stall in a predictable way.
| Circle | What it gives you | What happens without it |
|---|---|---|
| Something you have done | Detail nobody else has | Generic prose; you lose interest by chapter five |
| Someone who needs it | A reader, and a reason to finish | A finished book nobody finds |
| Narrow enough to cover | An ending you can reach | Scope creep; abandoned at 60% |
People usually have the first and skip the second, or have the second and are too broad on the third. The overlap is smaller and less glamorous than the idea you started with, and it is the one that gets written.
The two tests
Before writing anything, answer both of these out loud. They take five minutes and they save months.
Test one: name the place. Where does your reader already gather? A subreddit, a Facebook group, a professional association, a Discord, a WhatsApp group, a conference, a shop. Name it specifically. "People interested in productivity" is not a place. "The r/smallbusiness thread that appears every January about bookkeeping" is.
If you cannot name the place, you cannot reach them after publishing, and the book will sell to nobody regardless of quality.
Test two: write the subtitle first. One line that names the reader and the outcome. Not a clever title — the plain subtitle.
- Fails: "A guide to modern productivity"
- Passes: "How to run a one-person bookkeeping practice without working weekends"
- Fails: "Reflections on grief"
- Passes: "The first year after losing a parent, for people who have to keep working"
If the subtitle needs two lines or an "and", you have two books. Pick one.
Narrow is the whole trick
The instinct is that a broader subject means more readers. The opposite is true, for three reasons that compound.
- Competition. A broad subject competes with every well-funded book in the category. A narrow one competes with nothing.
- Recognition. Readers buy when they see themselves. "For people who run a single-chair barbershop" is bought instantly by those people and ignored by everyone else, which is fine.
- Finishability. A narrow subject has a natural end. A broad one never does, which is why it gets abandoned.
Narrowing is not shrinking your ambition. It is choosing a fight you can win, then writing the next one for the same reader.
The interesting idea is usually the wrong one
The idea that excites you at the start is often the one with the least material behind it — it is exciting precisely because you have not done the work yet. The book you can actually write is usually the boring-sounding one you have lived through and could explain to a friend at a kitchen table for two hours without notes.
A useful prompt: what do people already ask you about? What have you explained more than three times? That is the book, and the fact that it feels obvious to you is exactly why it is valuable to them.
Fiction is a different decision
Everything above is about non-fiction, where the subject does most of the selling. Fiction works differently: nobody buys a novel because they needed a novel about that topic. They buy it because of genre, cover, and word of mouth.
If you want to write fiction, write it because you want to write that story. It is a harder first book, it takes longer to find readers, and the economics only work over a series. That is not a reason not to — it is a reason to be clear about which game you are playing.
A short exercise
- List five things you have done, survived or been paid for.
- For each, name the group who is going through it now, and where they gather.
- For each, write the one-line subtitle.
- Cross out any where step two or three was hard.
- Of what is left, pick the one you could talk about for two hours without preparing.
That is the book. Write a plan for it before you commit to the whole thing; seeing the chapters laid out kills a weak idea faster than anything else.
Neubook interviews you about the idea first, then shows you the whole chapter plan before a word is written, so a weak subject is obvious in about a minute rather than at chapter nine.
Write a book, freeSources
- Amazon KDP royalty rates
- Google: creating helpful, people-first content
- The long tail, and why narrow subjects find readers
- Nonfiction, and its conventional forms
Common questions
How do I know if my book idea is good?
Two tests. Can you name the specific forum, group or community where your reader already is? And can you write the subtitle in one line that names the reader and the outcome? An idea that fails either is too broad, and broad is the most common reason books go unfinished and unsold.
Should I write fiction or non-fiction for a first book?
Non-fiction is far easier to finish and to sell, because the subject does the selling and the structure is given by the material. Fiction is the harder first book by a wide margin. Write fiction because you want to write that story, not because you want a book.
What if my idea has been done before?
Good. A subject with existing books has a proven audience; a subject with none usually has none for a reason. Compete by being narrower or more specific, not by finding untouched ground.
How personal should the book be?
More than feels comfortable. The specific mistake, the real number, the actual Tuesday are the only parts nobody else can write and the parts readers remember. Generic advice is what they can already get free.
How long should my first book be?
Shorter than you think. 25,000 to 40,000 words for practical non-fiction. A short book that is finished and read beats a long one that is abandoned at chapter nine.