Peter deSeve, famous for his New Yorker covers
did a tutorial that was in this magazine years ago and I finally found a link to it on-line.
I was kicking myself for not getting the magazine when it came out.
The magazine is apparently no longer published.
His work is just fabulous... loose fluid fun stuff.
The tutorial a pdf actual page size is here...
Peter also has developed the characters for some movies including Ice Age.
He has a book out that I just ordered... "A Sketchy Past" that I've seen rave reviews on.