Buy your tickets in advance, you don't want to waste time at the front of the park buying tickets, you can buy them online at each parks official site. In most case you can buy them online and print them from your printer. You can also have them mailed to you. Either way it allows you the headache of waiting in line to buy them when you arrive at the park on a crowded day.
Be sure to check the weather before you go out to the parks, Florida is not the "Sunshine State" it's the "Rainy State" so check the weather reports on the local news channels. It might look beautiful outside and in an hour you get caught in a severe thunder storm. .
If you don't want to pay Theme Park prices for food you might like to pack a cooler in you car and fill it with sandwiches, you can always leave the park and come back if you get your hand stamped. It might sound stupid but I have seen families eating lunch in the parking lot from a cooler in their car. You can bring a backpack with you inside the park with drinks and snacks so you can do it that way if you want as well.
Bring some Advil or Alieve with you, if you are not use to loud noises and thrills of a theme park you'll probably get a headache fast, plus if you are not use to walking a lot or being on your feet all day you will start to feel it and nothing is worse then standing in line with your back or feet hurting and having a headache that will ruin a vacation really fast.
You may want to bring your bathing suit or a change of clothing when you go to the theme parks. Some of the water rides will get you quite soaked. There are rental lockers where you can store your clothes. Some people even wear their swimwear underneath their outer clothes, and strip down to their bathing suits before boarding the water rides.
If you tend to burn easily in the sun you might want to put on some sunscreen before heading out, towards winter time the weather is nice and the sun is shining bright and since it's in the 60's to 70's you won't feel your skin burning.
Theme Parks are notorious for spreading germs, you have foreign visitors from countries with diseases like Bird Flu, and you have guests who come to the parks with colds, stomach virus and the flu; so it is a good idea to bring some hand sanitizer with you... if not wash your hands as often as you can especially before eating anything.
Bring your Camera Equipment, I don't really need to explain the logic behind that. Make sure you do have extra batteries, film and tapes for your cameras so you don't have to search all of the parks for expensive replacements.
Show up to each park at least 30 minutes prior to opening, so you can pick up your tickets early and get an early start getting on rides before the crowds take over the parks around 10:30am. Head to the newer and more popular attractions first thing, because those will be the busiest attractions during the day..
The Theme Park crowds will reach their peak at around 11am, so if you are planning a full day and you may want to take advantage of Fast Pass (Walt Disney World) & Express Pass (Universal Orlando) services to bypass long lines.
