Here's a mock book cover I've put together for my portfolio: Fictional book, fictional author, fictional character.
Here's a closer look at Cecily:
I put all this together in Illustrator, playing around with using outlines in my vector work, which I do't usually do. I quite like the effect.
The "Publisher" is the one I used to use when putting together booklets for school projects – named after a pet mouse I had when I was 12. I gave it a new logo for the purposes of this cover, but kept the original name.
I started out with a sketch I drew while watching The Mrs Bradley Mysteries, which is where the idea for YA detective lit came from when I decided to turn it into a cover instead of a stand-alone image.
Adobe Illustrator CS6. Not sure how long.