For the new brief that I was assigned I looked at what makes a good book cover and I found some interesting sources:
This link contains a list of the 50 best book cover designs of 2012, many of the book covers are very unique and creative using anything from photo manipulations, illustrations and typography to entice potential readers. I found that most of them seemed to communicate what the book is about by its imagery without almost having to read the text. Even the ones that weren’t obvious, became so once you read the text and the content soon became apparent. They have also have an appropriate use of typography according to its content.
I also wanted to have a look at motivational books in specific, so I thought that looking at highly ranked books on the subject (for their content) would help give me ideas into how these kinds of books are usually marketed.