The (Basic) Process for the No Doubt “Push & Shove” Illustration: (Tony Kanal) 

1. The Black Prismacolor Portrait (Sans detailed Hair) 

2. The First Idea - Layout with Light Blue Prismacolor (Only Close Photo Available - oops!)

3. The Rough/Cleaned Up IDea - Layout on top of Previous stage with a Dark Blue Primsacolor 

4. The First Inking - Done with Fine Point Sharpie, Ultra Fine Point Sharpie, and #01 Pigma Micron

5. The Fine Tuning Stage & Shading with Black Primsacolor (This stage is new, usually I would not add shading)

6. (Still need to high-res scan of the final with intended group layout + single layout)