1. Get up and out early, before the heat of the the midday
2. If your DD tires easily, consider a stroller for her. Remember, it will be hot, crowded, and therefore more tiring.
3. During the heat of the day (say noon-4PM), go back to your hotel, rest, swim. The parks are open later, so you can go back out at night and still see and do things.
4. Remember, it's vacation!!!! Don't try to jam everything in, don't "commando" tour...everybody will just get hot, tired, and cranky!!!!!
5. Have a basic plan and try to stick to it, but be open for changes if something good is happening somewhere.
6. Use Fastpass. It will enable you to see more attractions and still go on the ones you want.