One way to market children's and young adult books is through school visits. One school not only want me to be part of their "Meet an Author" day and discuss writing, but they also want me to put together a classroom packet (books, teacher's guide, and tests) for those book to be used in classes.
Some libraries have children days on Saturdays during the school year and weekdays during the summer. One of the 4RV authors has been invited to participate in one those programs.
I'm trying to create pamphlets to mail to school and/or libraries to get some scheduled workshops or teacher in-service for myself and other authors in our company.
The more access to people and more ways to promote ourselves means more sales.