The artist and writer Robert Genn publishes a free twice-weekly newsletter for artists. He is a thoughtful and eloquent writer and his topics deal with such matters as criticism, motivation and inspiration. (Thank you, Karin Wells for letting me know about this newsletter.)
His most recent letter deals with turning down a commission. I also liked the one I received last week dealing with interruptions (and in fact I think I'll start such a topic here myself).
You may subscribe at this link:
http://painterskeys.com/subscribe