Although this book is aimed at comedy writers of jokes, gags, sketches and sit-coms, the self-taught approach Perret describes is applicable to so many other fields.
Gene Perret is a veteran comedy writer having worked for Phylis Diller and for Bob Hope for thirty years. His training approach is to have you adopt a comedian as a mentor and to study that mentor in depth. Try to write for that comedian and, if you can get that comedian to perform some of your work, so much the better - tricky if your mentor is Bob Hope, though.
A good book, lots of ideas and lots of anecdotes from a lifetime in comedy.