Evaluate the time of year you are going. Summer is easiest to pack for. It will be hot, probably 90 degrees plus during the day and 70s during the evening. Spray fan bottles run close to $18 at theme parks, but you can buy similar ones at a discount store for about $5.
Prepare for dramatic temperature shifts if you are going in winter. It can be mid-70s or 80 degrees one day and 50 degrees the next. Take a winter coat with a zip-out lining, hats and gloves. Wearing layers is key for winter visits. Convertible zip-off pants cut down on how much you pack. Mornings often start off chilly, but by midmorning you wish you were in shorts. When the sun goes down you will wish you had your pants back. Sweatshirts or fleece pullovers are another important item for winter.
Know that it will probably storm for awhile on most afternoons during summer. Take disposable ponchos and mini umbrellas that you can carry in your day bag. Disney will of course sell them to you, too, but they will be more expensive.
Bring string backpacks. They are lightweight and durable. Many also have water bottle holders. Also take plastic bags to store wet ponchos or umbrellas.
Remember batteries for cameras and spray fans. Bring a spare set for everything that takes them, as well as phone chargers and extra camera memory cards.
Don't forget hats, visors, sunscreen, hand sanitizer or wipes, clothing spot cleaners and a few first aid supplies. The Florida sun can be intense -- slip a travel size sunscreen in your day bag, too.
Wear good walking shoes with good arch support. You can rotate your shoes and sandals, but you may find the best support comes from a good pair of tennis shoes. Sandals are good for the water rides, but many do not offer good arch support. Sore feet and legs will ruin your day.
Take any over-the-counter or prescription medicines you need. Bring a small assortment "just in case."
Don't forget lanyards, fast pass holders and eyeglass cases and straps. Just one less thing to worry about on those rougher rides.
Bring snacks. Crackers or granola bars can fend off that shaky feeling when you're in a ride queue and hunger strikes.
