Every potential author should ask the same kinds of questions:
- Am I the right person to write this book?
- Does my book really make sense?
- How is my timing?
- Does the book meet a clear market need?
Let's take them one at a time.
Are you the right person?
You're the right person if you feel passionately about the topic; you have solid, quantifiable experience in the topic and consider yourself an expert; your credentials indicate that you have a reasonable background to write expertly about the topic; and, for a textbook, you have substantive experience teaching the topic to learners.
Take this example. Betty is a CMA (AAMA) with a BS degree in, say, biology. She is also an RN and has been MA Program Director at a community college for 6 years. She wants to write a book about clinical skills for MAs. Does she have what it takes (superficially, at least) to author that kind of book? I'd say yes, absolutely, she seems to have a good skill set for that.
What if Betty wanted to write a book instead about teaching skills for new allied health faculty? Does she have what it takes? I'd say no. She might be a great teacher but her educational credentials don't support her being an expert on the topic. For a book like that, she should probably have an Master's in Education and have a substantially broader experience than solely in medical assisting.
Does the book make sense?
By "does the book make sense," I mean is the topic is broad enough and pertinent enough to sell a significant number of copies? Some topics are just too small for a book but would make a great journal article. They're so niche-oriented that it wouldn't make sense for most publishers to invest in a book that won't sell enough copies to turn a profit.
If your book would fit a course you know is offered by all or most programs, then you've got yourself a solid idea. If it would fit some programs but not others, or if the book covers a section of content within one or more courses, you'll have a more difficult time "selling" it to a publisher, but go for it anyway.
How is my timing?
For courses that already exist, such as med term, A&P, pathology, and the like, timing isn't critical. There are already books out there and the course already exists.
But for topics that seem "cutting edge," topics that are on the cusp of becoming standard but aren't there yet, you're in a tough spot. Some publishers certainly will risk taking on your book, but because education in general—and healthcare education in particular—move so slowly, most publishers will have second thoughts about publishing it. Which leads well into the last question…
If the topic is too new and untested, then deciding whether your book on it would meet a clear market need becomes much more difficult. The safest book for a publisher, the one with least risk, is one built to compete with at least one other similar product. In that case, it's a let's-do-ours-better kind of approach, which is a nice approach to have. Build a better mousetrap, eh?