Tom Richmond has written just that book, called The Mad Art of Caricature!: A Serious Guide to Drawing Funny Faces.
Richmond is best known as one of the "Usual Gang of Idiots" at Mad Magazine, but he has worked as a freelance illustrator for lots of other major clients. He got his start doing theme park caricatures in 1985.
|David Lynch by Tom Richmond|
Richmond explains how to analyze an individual's appearance to recognize what's unique about their head shape and their attitude. He talks about how to exaggerate the distinctive traits, rather than randomly distorting.
First you key in on the head shape, and then the main shapes within the face (eyes, nose, and mouth), and, importantly, the spacing between them.
He analyzes each of the features, as well as the chin, cheekbones, and hair, considering carefully how they change with different angles and different expressions.
Instead of seeing the features separately, you learn to group them. Richmond came up with the "T-Shape Theory," where you group the eyes and nose into a single shape within the face, taking note of the length and width of the T.
Tom is a good writer and teacher as well as a good artist, so this book is really worth reading carefully. The layouts are loaded with many drawings and diagrams on every page. It wraps up with a discussion of the challenges doing live caricatures, caricatures in illustration, and how he constructs a complex multi-figure scene for MAD magazine.
Tom Richmond also has an excellent blog that is constantly updated with new work and teaching.
On Amazon: The Mad Art of Caricature!: A Serious Guide to Drawing Funny Faces