DESIGN satisfies our esthetic sense of what a "real" book should look like. Barbara Ward gave us the metaphor of a crystal goblet as the perfect vehicle for wine— unobtrusive but highly functional, in fact getting out of the way of the experience of the wine (or ideas) to the point of invisibility.
EVERY BOOK IS UNIQUE. The book designer should strive to represent, to the best of her or his abilities, the book and the author in the presentation of the physical book, right down to the well-chosen font, point size, leading, white space around the words.
Book design refers to the interior pages. If you intend to sell ebooks only, then you can skip book design; the iPad or Nook or ereader simply streams text and lets you choose (or not) the font, the text size, etc.. For print books, however, good book design is essential to good reading.
Take a look at books that these designers have worked on; see what appeals to your sensibilities.
This is a list of active book designers.
Ideal book design for paper editions may seem easy and unnoticeable; if so, then the design is a successful match of content and delivery. The book itself is its best advertisement.
JOHN MARTIN, Black Sparrow Press. “For twenty-five years, Sasha has always responded with enthusiasm and initiative to the requirements of our demanding publishing schedule.”
THOMAS RYDDER, writer: “Thanks so much. This is actually the most insightful criticism I've received on any of my writing, and it's immensely helpful.”