As promised, here's a post on the process for the Ninja Turtles poster I put together. Before I drew anything, I settled on which incarnations were my favorites. Seven groups of four turtles (+ Master Splinter, April and Casey) added up to close to 50 characters in one composition.
From there, I started organizing the figures, sketching them digitally:
Then I moved on to drawing more finished lines:
I added the basic colors:
And I added the final rendering:
And just for fun, here's an animated gif, showing the whole process (click for a larger view):