The trim and the technical details are probably the least important things (your designer will ask you about the basic specs if he/she doesn't know them). Your job is to figure out what you want from your cover artistically. read more
For a completely different perspective on the question, you may want to see an article I wrote for Writer's Weekly in 2010 called Common book cover design errors. I wasn't looking at the design from an artistic point of view, but from the practical point of view of a bookstore owner. read more
A list of things designers should ask their clients before starting to design a book cover. read more
12 Questions to Ask When Hiring a Book Cover Designer October 8, 2015 by Diana Urban Your book’s cover provides a reader with a first impression of your work, and despite all advice to the contrary, people will judge your book by its cover. read more