Creating a visually dynamic illustration for a front cover is always the result you want to achieve when starting the project. For Twisty Tales, The Little Mermaid Adventures commissioned by Franklin Watts the challenge was creating a cover image before the work had started on the book interior illustrations.
Through the process of roughing out the concepts for the interior you take your characters designs and get to know them better in the actions they take throughout the story. The character design changes and adapts to the highs and lows of the adventure. Little tweaks to the look can help express emotions better and it all helps with the narrative. Doing the character design illustrations first for the book cover is not unusual as long as you know the story and the adventure the characters must face.
I develop my sketches in pencil and hand them over for review, keeping a good line of dialog going with the client and adapting the concept illustrations to fit with the feedback. Ensuring a quick pace at this stage keeps helps the development and the input fresh so that the character doesn’t get overworked.