The biggest one it to go during value season whenever possible. The room rates are much more affordable and the parks are less crowded.
The first year we went (2/04), we bought annual passes because it was cheaper than the day-by-tickets for the length of our stay (I believe that was before the Magic Your Way deal). We planned our second trip for the next year, two weeks before the passes we due to expire. So basically, it was like getting two entire vacations out of the same set of passes. That was a huge savings, albeit a long term one.