As you probably know, Walt Disney World is a huge resort with a multitude of things to do. To avoid a hectic and possibly disappointing vacation, some amount of planning is required.
-For example, find out when parades are taking place at the park you are visiting. If you have already seen the parade or are not interested in seeing it, this is a good time to see one of the more popular attractions, as lines are generally shorter.
-From August to October is the hurricane season in Florida. During these months the parks are less crowded. I went to Florida in August and although it may rain nearly every day during this season, the showers are often short and very light. Having a plastic rain parka can make this a very minor inconvenience. We had a fantastic time!
By the way, there are several behind-the-scenes tours available at Disney World. They usually cost extra and in some cases involve a lot of walking, but if you have the time and the money they are great. You get a chance to see the hidden technology behind Disney World that no one ever sees.