1. Getting the idea
2. Fleshing it out
3. Perspective and the fisheye
4. Details and all that clutter
5. Storytelling
6. Final sketch
7. Inking
8. Fixing the lineart
9. Flat Colors
10. Hide in the shade
11. Finishing touches
A step by step I've prepared for 3D Total. I couldn't fit the entire description here, so you can read the entire article here http://3dtotal.com/tutorials/t/combine-traditional-and-photoshop-methods-to-create-a-narrative-illustration