I don't think anyone really knows. I think the best bet is just to sign up for all of the Disney mailing lists, get a vacation planning DVD, DVC information and so on.
One way is to register on the disney web site. Then there are questions as to whether you are interested in receiving e-mails and offers from disney. Make sure you check those boxes. Also you should request the vacation dvd. These things can help, but who gets the pin codes is still a mystery.