Scott McCloud’s Understanding Comics and Making Comics are of course essential reading for fine and sequential artists working with the relationship of text to image. I have spoken at length (with varying degrees of coherence) about the fascinating relationship of comics to fine art (narrative, pacing, spatial concerns, framing, etcetera, ad nauseum, ad infinitum)…but don’t forget book covers!
The inestimable David Butler is of course doing an entire series of paintings which manipulate this relationship in the context of romance book covers.
What about an actual book cover designer? Well, the only name I know is Chip Kidd. Luckily, he happens to have a fantastic TEDtalk on this very topic! He doesn’t tell us everything about how the exterior of a book can relate to its content…but it is a good start.
(An especially useful section is 2:53-3:44)