Since most of the story and humor is told in the pictures, and all I'm submitting are the words, how do I tell them what needs to be included in the artwork for each page?
I've written it by page, but the first thing I do, in parentheses, is describe the basic elements needed in the art. The text follows.
I don't want to violate the author's copyright by giving you all of his advice, but I'll give you a partial quote:
Many authors...want to include guidance for the illustrator for the manuscript.... Including this attempted guidance in a manuscript is a bad idea.
You'll have to get a hold of the book to hear his explanation, but suffice to say the gentleman is an industry professional.
What I recommend is reading your manuscript to see where a description of the visuals is absolutely necessary, and where it can be inferred. Where it can be inferred, remove the parenthetical paragraph. Where it can't be inferred, remove the parenthetical paragraph anyway! Then do the most minimal rewrite possible to where the text does infer an appropriate image.
Illustrators are the equal of authors in the picture book business, and they value their autonomy. They see themselves as artists, not order-takers - and rightfully so. Make sure your text says what it needs to say, then when (fingers crossed!) you get published, you're likely to pleasantly surprised at everything your illustrator brought to the table.