My friend and fellow illustrator Paul Fricke recently sent me a great link:
Dave Roman has been working at Nickelodeon Magazine for the last nine years. He is also a frequent lecturer at the School of Visual Arts. This article summarizes his advice for art students just starting out in illustration, comics, and/or cartooning. I’ve been freelancing for over ten years now, and I agree with what Roman has to say. His article is packed with good advice for the beginner (or even the not-so-beginner).
Along the same lines, here’s another great article I’ve blogged about before:
17 Lessons on Freelancing by Megan Jeffery.