Step One:
Write A Book
Easier said than done.
True but what concerns us here is HOW MUCH book to write.
Killing John Kanton has 87,700 words and is 332 8½ by 11-inch (portrait) “pages” long. A “page” has one-inch margins on all four sides and the text is formatted in Courier New 12-point double-spaced (24-point height). In the hand-made book described here, this fills 10 signatures, which includes front matter and cover pages. Swedging has 75,430 words and fills 300 pages and nine-and-a-half signatures. American Providence has 111,243 words and fills 482 pages and 12 signatures.
A signature is made up of eight pieces of 11 by 8½-inch (landscape) paper folded in half. It contains two pages on each side of each piece of paper, so there are four pages per piece of paper, and 8 * 4 = 32 pages per signature. So, 10 signatures has 320 pages. You can see that, using this design, your rough copy closely predicts the length of your published hand-made book.
These same books published as 6X9-inch on-demand books had Killing John Kanton take up 308 pages and Swedging take up 291 pages. Again, your rough “pages” predict the length of your books. Be aware, however, that the published book’s typeface and font size and line height may differ from the design described here and would thus draw these calculations into question.
Suffice it to say I would find a seven-signature book kind of skimpy and a twelve-signature book hard to handle. Still, both can hold a compelling work of art. Consider A Christmas Carol (38,000 words) by Charles Dickens and Harry Potter and the Goblet of Fire (190,637 words) by J. K. Rowlings. A Christmas Carol might fill three signatures and Fire might run 20 signatures (a cumbersome handful).
The design used for Killing John Kanton and Swedging uses 11-point Palatino on 14.75-point lines. If we made the font small enough and the line height small enough, we could fit Harry Potter and the Goblet of Fire into a 10-signature book too, but it would not be pleasant to look at or read.
So, the first step is to write a book that tells a compelling story. A significant part of this step is to have the book edited by a trusted editor who will ask you hard questions and bring out the best in you as a writer and make the book the best, most professional work of art possible. You and your editor should agree on a stylesheet to use. I trust the Chicago Manual of Style. My editor asks for $1 per page in compensation. Expect to go through at least two rounds of editing.