But then my sister becomes a production designer for films, and voila! She has an instant art/graphics team (my mother and me).
It really feels like any other illustration or graphic design assignment - you start with concept sketches, then move on to the final version once one is approved. Or if the schedule's really tight, you trust your gut and go with what you think would turn out the best.
You [almost] forget what it's being used for, so that it's almost a surprise when you see something you've worked on in a film clip:
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http://abclocal.go.com/wabc/video?id=7871234
(Keep an eye out for the wild-dog patches on the uniforms, pain-stakingly drawn in Illustrator with a Laptop mouse) :-D
Check out my IMBD page for some of the films I've worked on the art for:
http://www.imdb.com/name/nm3973440/