How does that translate to how I work with them?

You need to have some sense of what you want. Not specs like font/leading, but what kind of design in terms of contemporary, traditional, minimalistic, etc. Look at books whose design you like -- though not necessarily want to copy -- and figure out what you want. Start with that.

On a project as big as a book I'd start by finding a number of designers that you think you might like. Then schedule a time to sit down with them an examples from their portfolio and talk in very broad terms about layout ideas that you like or dislike and look through their portfolio for layouts that strike you as heading towards the style that you like.

The next step from here is going to vary a depending upon the person you are working with. They may want some broad form mock-ups from you, they may want to mock up some example sections on their own and then run them by you for review and approval. Once you are headed in the right direction then you need to set up very clearly defined milestones and buy off points. This will help catch areas where your two design ideas may be diverging.

My experience working as a creative professional is that I can give my clients the most when we are regularly checking in with each other and there is an open line to push each other's aesthetic. My clients will almost always bring something to the party that I wouldn't have thought of, and I will almost always bring things to them that they hadn't considered.

But font is one of the decisions I want a professional to make.

Then you need to let them know that and delineate it in the contract. Because I have worked with clients who have said similar things and then shot down not one, not three, but four sets of specs I gave them, after they said the -- I don't mean to be snarky -- very disingenuous statement "oh, you decide that! You're the professional!"

Also - each 2 page layout will have three components - a graphic, a very short text, extended text. I want to reader to look at the graphic first, then the short text, then the extended text. A layout artist is the person figure out how to do that, not me.

Right, but you need to be able to tell them what you just said right there. So that paragraph -- that's a good start.

Wait. I obviously skimmed, but I just went back and read the pertinent posts -- Typo, what is your publisher creating out of your content? It sounds like not a book. Am I wrong? Are they not doing the layout and design of your content? And if not, how are they publishing it? IOW, what format? Are they making an actual physical book, or something else?

OK what my current publisher is creating is a book. A book that is all text except for 18 graphics out of 210 pages. (16 of the "graphics" are tables so not what I normally think of as graphics.)

I want to create a graphic supplement. 200 pages, but mostly graphics with less than 10,000 words of text (maybe a lot less). In the supplement I envision, each 2 facing pages that includes: 1) A large graphic 1/2 to 3/4 of the page (not including margins). A single sentence that combined with the graphic conveys the key information in those 2 facing pages. Extended text that explains in more detail, gives an informal citation if the point needs proof and tells where to go for more information (about 100 words on average perhaps less). The book my publisher will release in Novemember is very academic. This supplement is intended to be informal and (if it is OK to use the word on a horrifying subject) entertaining.

Instead of Entertaining, try Engaging.

Engaging is indeed the right word.

Are you planning to sell this supplement, TB?

I am. Why I'm willing to pay for professional help. I hope to make money off it. My publisher will not sell me discounted copies of the main book to sell on a book tour. So if I'm going to finance a book tour I will need something to sell, and this will be it. It is why I think I can actually sell something self published: I will be there in person selling copies one at a time.

Okay, that clears it up for me. I was wondering why you weren't having the what-will-the-book-look-like convo with the publisher. (Uh, not that publishers really allow authors to have all that much [or any] input on the design.)

Do you anticipate different audiences for the less-graphic-intensive book (the one produced by the publisher; henceforth referred to as "the book") and the more-graphic-heavy supplement (self-published by you; henceforth referred to as "the supplement")?

If you anticipate (or hope for) overlap in audiences, I feel very strongly that the supplement should have some graphical elements that are the same as/similar to the graphical elements in the book.* Those tie the two together in the readers' minds, even if they don't consciously think about it.

(This is my own opinion about design; I believe it's the prevailing opinion, and one that's taught in design classes -- that you should tie produced pieces together visually. Obviously not all designers believe that, nor do they do it. And of course, the people paying the designers don't always want it, for whatever reason they may have. All that said, it's something I've always suggested with clients for whom I've produced more than one piece. Sometimes it's been as simple as keeping a specific Pantone color and using the same distinctive font. It's a principle Chatty and I try to push at work, because we want readers of our journal to associate our textbooks with our journals, but it's a losing battle with TPTB. They love everything to look radically different from everything else, and, in the end, they're the ones who sign our paychecks. I simply refuse to put the textbook with the blue cover and teal text [I am not lying] in my portfolio.)

*And having similar graphical elements might not be possible for you, if the book isn't completed (or even in production) before you begin production on the supplement. If you don't know what the book will look like, you can't retain some graphical elements for the supplement, and I get that.

Something to think about.