If this is for the character meal at CRT, check out the thread here:
http://www.disboards.com/showthread.php?s=&threadid=195400
I think the biggest tip is to start calling so it will ring as soon after 7am (eastern) at the 90 day mark for the first date you want the PS. If you don't get it that morning (and I've read they fill up within the first 10 minutes after the calls start at 7), try each morning after that for the next day of your trip. I've seen posts where the writer indicated he/she had 2 or more people making calls to increase their chances (if you're working with a TA such as
Dreams Unlimited or are staying concierge level, you can get help from them).
If you don't get a PS, don't despair. Some people have had success calling again later because some of the original PSs are cancelled (people with more than one). Also, some DIS members post here when they are releasing their PSs to help other DISsers.
If you just want to have a breakfast with Princesses and don't have to see Cinderella, there is a second breakfast option in Epcot at the Akershus restaurant. This is called Princess Story Book (PSB) and is much easier to get a PS for it (I called at about the 60 day mark and there were no CRT PSs available but there were options for most of the days of our stay for PSB).
Finally, I've read at least a few comments that some people have had success as "walk ins" for CRT or when they called within 48 hours of when they wanted to go. Since you must use a CC to get a PS for CRT or PSB, people are much more likely to cancel a PS by the 48 hour window than places where they wouldn't be charged for a no-show.
