A New Start for Wilberforce Wolfe - children's story

I have written a series of children's books, aimed at children 6 - 8 years. They are not classic children's picture books, but early readers, and will have pictures interspersed with text. I intend to publish these books as e-books and my suggestion is that I would team up with an unpublished illustrator. I can't pay anything up front, but would pay the illustrator 25% of all sales on an on-going basis, for as long as the books are available. This arrangement would be in place for the first three books in the series. I provide the text, the artist provides the cover and an agreed number of illustrations. If the series sells well and both parties want to continue the arrangement, that could be agreed. In order to determine the best artist for the material, I propose to ask interested artists to submit two or three illustrations in response to Chapter One of the first book. I would leave the content entirely to them. I would also discuss in more detail the nature of the partnership before any illustrations were started, in order to avoid anyone wasting their time. If any illustrators are interested but would like more details or to discuss the proposed arrangement, I am very happy to enter into a conversation.