My first two attempts at making mock book jackets are below - LOTS of parts and pieces to consider (this is quickly becoming the norm for these things!). The book design files were then uploaded into another Photoshop file that acts as the “template” or the general display setting for the design, aka the “fake room” the design is floating in.
These two examples were made entirely in Photoshop, and I believe the next book jacket design will be in Illustrator, which I have just begun in learning in the second part of the course. Cue my head getting ready to explode!