I send out postcards to editors and art directors at least once if not more every year. I print them at www.modernpostcard.com

I also "cold call" editors and art directors in New York and schedule interviews to have them look at my portfolio.

"The Business of Illustration" by Steven Heller and Teresa Fernandes (available used or at your library)

Join the SCBWI at www.scbwi.org It will be a life saver as far as gathering your mailing lists are concerned.