Sketch

I first sketch out the rough version of the artwork.

Lines And Flats

I add lineart in a separate layer and then color in all the flat colors. I also add the name onto the banner.

Shading

I now add the shading using clip layers and multiply. I add shiny bits with the luminosity feature in SAI with an airbrush.

Finished!

I add a paper texture on top for a grungy look on overlay.