Not sure what to include in your portfolio? Here’s a checklist I’ve been compiling for the past few years. I’ve been a member of SCBWI since 2002 and have served as an Illustrator Coordinator for the Rocky Mountain Chapter since 2009. I also teach children’s book illustration at the Rocky Mountain College of Art and Design. It’s safe to say that I’ve seen my share of working (and not-working) portfolios.
These are suggestions rather than rules, but if you have most of this list, you’re going to be in great shape for your next portfolio showing. Good luck and happy creating!