What about academics writing for a general readership?
Scholars often have excellent material for a general audience of thoughtful readers. But commonly, academics underestimate how much they will need to change their writing style to reach that audience. Often I will get a proposal from a professor who says the book will be for lay people. But it is clear from the writing sample and the proposed table of contents that it is a text for graduate students–several levels above the supposed target audience. Authors often assume knowledge of high-level vocabulary that general readers won’t have.
don’t want lots of footnotes, don’t want to know about your methodology and certainly don’t want a literature review. They expect you to write in first person active voice, not third person passive. They don’t want you to wait until the last chapter to hear something practical. That should be found in every chapter. General readers will need stories and illustrations to keep them motivated. They will need concrete examples throughout to help explain the theory you present.
Often academics have the ability to speak effectively to lay audiences. If that is your situation, try to write like you talk. If it is not, then you might try to find opportunities to speak to lay audiences so you can hone your skills in reaching them.
What are academic publishers looking for?
Academic publishers usually do books in four categories: core texts, supplemental texts, monographs and reference books. If your proposal doesn’t easily fit in one of these slots, you’ll probably have a hard time getting it published.
Where do textbook ideas come from?
Often good ideas for new texts arise when professors just can’t seem to find a text for a class that covers what they want their students to know or they way they want to cover it. So they turn that frustration in a positive direction and try to write it themselves.