I am often asked about my process in designing book jackets and my initial response goes something like this: each project is unique and it 'depends....' A vague answer, I'm afraid. *laughs* I first ask the client about their manuscript, then make inquiries about favorite colors, other book covers that they favor and if they have any specific elements they'd like to see on the cover.
Then I begin my concepts (in Photoshop, not by hand which usually surprises folks) based on the client's input and largely on my own gut instinct after interacting with the client. I like to work directly with the client in developing a cover design that truly speaks to them and represents the story that they are telling within the pages of their book. While my education taught me the 'rules' of formal graphic design, I often step outside that box and go for something more unique. Not all publishing houses allow my sort of free styling in book cover design, but I certainly push that envelope!