Have you checked out the Professional Child Photographer FAQ pages at http://www.professionalchildphotographer.com ?
Back in 2007 myself and a small group of photographers pooled together to create ideas for this amazing resource. It has helped photographers all over the world educate their clients on the costs, benefits and beauty of custom photography. Please spread the word on this amazing resource!
I am so proud to be the admin for this site and love that so many photographers take the time to send me emails about this resource. I hope that my goal of helping to educate your clients via a third party is helpful. I always welcome suggestions – if you have article suggestions feel free to drop me a note.