The answer? Don’t. Not because you aren’t good, but because the publisher wants to do it.
The Society of Children’s Book Writers and Illustrators (SCBWI) says, “The editor who purchases your picture-book manuscript, or the art director at a publishing house, will ultimately choose the illustrator.
SCBW says, “Except in rare circumstances, it is seldom a good idea for authors and illustrators to collaborate together before publication.” They also say, “There is no need to describe the illustrations in your submission. If your manuscript doesn’t come to life visually without being explained, then it probably needs work.”
If you’re going to self publish, research the kind of illustrations you will need to help sell your book to readers. Illustrations come with an underlying tone, feeling and suggested meanings more than you might think. Illustrations are too important to leave to chance and the fact that you like them doesn’t necessarily count.