A link to the blog Market My Words, with an interview with Abigail Samoun, editor at Tricycle Press, posted on the SCBWI-Illinois list serve. Abigail gives three very concrete ways that authors/illustrators can promote their books, and she makes it clear that "active" authors are a step ahead in the submissions process.
If you are serious about writing or illustrating for children, you will be a member of SCBWI and keep up with the list serve in your region. Members ask questions and trade information on the list serve. In Illinois we are lucky to have so many generous and experienced authors and illustrators who give freely of their hard-earned expertise.