On the www.gumbowriters.com blog I found some great tips on writing for children from free-lance editor Adriana Dominguez.
One question writers often have about picture books is whether they should hire an illustrator themselves. The answer is no. Publishers will make that selection.
Also, never try to “give
an idea of the illustrations” by drawing your own. And what is the format of you manuscript?
Dominguez says:
“A picture book, on the most part, is anywhere from 32 to 40 pages long, and they have about three lines per page. So, you are talking about an average of a thousand words or less. When I get a picture book manuscript that is single spaced, three or four pages long, I know that its author has no notion of how picture books work because I could fit four picture books into that amount of text! So submit it in a way that clearly lets the editor know that you know the standard format for picture books, and that the goal of that format is to visualize the text, hence, you probably want to divide it into pages remembering that each page should have only a few lines. Doing that will also help you realize what the picture book would look like and whether it will work in that format, before sending it to an editor.”
(Whatever kind of book you're writing, you'll find loads of helpful, friendly tips in my book, "Your Writing Coach," published by Nicholas Brealey and available from online and offline retailers. The associated website is www.yourwritingcoach.com )