Career as Depicted in Popular (or Unpopular) Culture
Read: Comic strip anthologies. Cartoonists will often tell their "How I Got Started" story in the consolidated books of their daily strips. Larson, Bill Amend (Foxtrot) and Adams did. So did just about every other cartoonist whose work was popular enough to justify anthologies.
Watterson gave probably the most in depth description of his work, his inspirations, and his road to becoming a syndicated cartoonist in The Calvin and Hobbes 10th Anniversary Book. Also, read Schultz and Peanuts: A Biography by David Michaelis.
See: Stripped—a documentary about comic strips that contains a metric ton of interviews with syndicated cartoonists, including the first ever audio interview with Bill Watterson. No joke; somehow they tracked the man down and got him to agree to answer questions posed by actual humans. It's possible blackmail was involved.
Also, see a sitcom from the late '90s called Caroline in the City. It was about a New York-based comic strip artist and her friends and their wacky misadventures in the city. Or something like that.