I'm not sure when my next one, CLOSE-UP, will be released, but I already have great, oversize postcards with the cover and the synopsis on the back with a favorite reviewer of the series quoted. I just put "Oak Tree Press, Fall 2011" at the bottom. This way I can give them out at the local events I have scheduled and, hopefully, whet some readers' appetites! It's good to order these postcards as early as you're able because, believe me, when they advertise "Overnight," they're being very optimistic!
Also don't forget alumnae magazines. My college puts out a beauty and was happy to share my book news with a bit of info on the new one to come. Plus they added the fact that my husband was named Professor of the Year at St. Mary's College and we used to have "mixers" with St. Mary's boys way back then and HATED to go! We thought they were so geeky! Now they're co-ed, too. How times change.
So think ahead and do what you can for yourself and your new stories!
PS my daughter Annie Sperling, a production director in Hollywood, does my covers and we had fun with this one. It's part photograph and part pure painting with a dear friend of ours, Kim Andersen, acting the part of my protagonist, Margot O'Banion. I don't know how Annie manages to put these together, but I do love them and appreciate her time and energies spent on them. She works 17-hr days and somehow finds the time for her mum!