A writer asked:
If you have a bunch of book ideas, how do you decide which ones are viable?
Spend some time on each idea, one by one. First work on a rough outline of what the book would be. List the themes and topics you’d want to cover. Ask yourself: is there enough material here for a whole book? Consider whether you’ll be able to gather the information needed to fill a book on this topic. Is there enough to say?
Marketplace: Are there other books on this topic? Too many? Is there room or need for another one? Can you identify a hole in the market that needs to be filled? If there are no books on this topic, consider why. Is there a need but no one has filled it yet? Or is this something that people don’t want to read a book about?
You: Consider whether you’re the right person to write this book. Do you have any qualifications that would cause book buyers to trust you? Do you have a platform with which to sell this book?
The idea itself: Try to be honest. Is it unique, or derivative of many other books you’ve seen? When you talk with people about it, do they seem to get it? Do they respond with excitement, curiosity, inquisitiveness?
Put all your information together and a picture should emerge of each idea’s viability and chances of selling.
Others might have different advice, but I think you need to write the novel that is most on your heart and mind right now. Always save your book ideas in a file, and add to them when the muse strikes. But write the one that’s speaking to you.
Of course, you could carefully craft a one-sentence hook for each of your book ideas, then show them to a group of friends or fellow writers, asking them to rank the ideas in order of interest. This might help, if there is some similarity in their answers. Perhaps a clear winner will emerge. But be aware that you might get a variety of responses. So again, you’ll need to choose the book you are ready to write. With fiction, the idea is important, yet secondary to the writing.
You do need to pay attention to marketplace trends, but be aware they can change at any moment. What editors are looking for today might not be what they’re seeking eight months from now when you finish your novel.
If you haven’t sold any books yet, be aware that branding is important, so the first book you sell will set you up to begin creating your brand. Make sure that first book is something you want to write, and make sure it begins establishing a brand identity that you’ll continue.
How did you decide (or how will you decide) which of your book ideas to develop first?