Take aways from art directors and editors at the Austin Society of Children's Book Writers and Illustrators conference:
1. They still really love postcards. They called them one of the best ways to get your work in front of them. (They hang them on their doors and bulletin boards. Don't be discouraged if you don't hear back right away. They told the story of one illustrator whose card hung on a door for almost two years before getting a gig.)
2. Make it easy for them to see the work on your site and to download your images. Example of not ideal, they described hunting through tiny thumbnails to find an illustrators best work.
CSJennings.com (my site) is not currently user friendly in either of those ways. Redesign quickly being instituted (which was underway, but not with the urgency it now has).
Finally, in my experience, the best way to get published is A-to-B. Go where the book pro's are. SCBWI conferences are great for that. Schedule portfolio reviews, etc.