In Laura Busche's blog post "Hand-Sketching: The Things You Didn't Know Your Doodles Could Accomplish" she explains how sketching on *paper* takes her designs to the next level.
I met with another artist Saturday morning (10/13/13) who worked as a line illustrator. She learned most of her skills while on the job. Today she is retired but continues to draw and paint.
We spoke about how sad it is that today there are many graphic arts students who cannot fathom why on earth they need to learn how to draw on anything other than a computer screen.
I found Laura's blog article through Dave Kelley's blog post where he is collecting resources before, during and after the upcoming DevLearn2013 event.