Take a look at the process step by step of the John Carter‘s cover challenge, from the early (digital) pencils, references, rendering and final mokup.
After collecting some refs for the characters I started the pencil sketch.
The early princess was Bo Derek and John was Jude Law.
Underpaint the sketch with warm tones just to fix values and to give consistency to the shading process.
Composition tests are submitted on forum in order to receive feedback from fresh eyes.
Final version with lettering