My usual reaction to this kind of question is to run around in circles with my arms flailing wildly, screaming, “Don’t include illustrations! Editors and agents really, really, REALLY don’t want them!” And in most cases, they don’t need them. We writers sometimes forget that half of a picture book editor’s job is envisioning potential illustration styles for a story and then pairing the manuscript with an established illustrator. But in your case, the project is all-or-nothing, so here’s how to do it right: Include one or two color illustrations on a single sheet of paper in your submission package and then refer the agent/editor to your website for more illustration samples. Explain the scope of your project in the cover letter. After that, it’s up to them to decide if they like your text and illustrations with equal passion.