Some points to consider:
Know the various page count options available. Will your book be 32 pages, 40, or other (in printer spreads divisible by four). Typically, a picture book is 32 pages. That may or may not include back matter (Author/Illustrator notes, maps, charts), depending upon what's needed.
Beginning and end. Will your book use a pastedown method, which typically begins and ends with a solid paper color treatment. Or will your book use illustrated endpapers, which can be used as an extension of your story—or to provide more information.
Case covers. The case cover is the hardcover that the book is bound inside. Some case covers use a different design than the jacket that wraps the book, which serves as a fun surprise for readers.
|Case cover for Curato's What If . . . by Samantha Berger, differs from jacket flap.|
What a surprise!
Trim size. Will your book be sized in landscape (horizontal, wide), portrait (vertical, tall), or a perfect square. Keep in mind, a large horizontal book can present challenges for librarians when it comes to stocking the book on shelves.
During the second portion of Curato's workshop, he shared some of the thirty-something revisions he made along the way in creating the original Little Elliot. Great time!