Once, I was in a group project where we were focused on things we do in our free time. One of us liked to spend time in various café's, one liked movies and one liked playing football. Me, I just liked painting, so I painted them for the project's promotional posters.

This one was for the friend who liked playing football.

Down, you see some progress shots. From left to right;

Sketch > Base colors > Basic shadow > Basic light and background

After the adjustments, it's just overpainting, rendering and refining.