I'm looking forward to going to Orlando in August! It will be so nice to get away from the 115+ degrees that our summers have

I have family that lives in Orlando, and they can't stand the heat where I live. The last time they were here, one girl ended up passing out because they weren't used to the temperature.
Drink lots and lots and lots of liquids! I tend to forget this

I also have an allergy to the sun, and it makes me have horrid headaches and I can't wear shorts. I wear jeans/pants all summer long (I totally live in the wrong area). Excedrine Migraine helps out with the heat headaches, don't forget to pack some!
One thing to remember about heat is where your cooling spots are. Put something cold on your wrists, and on your head. I've seen the cool neck things that you soak in water and then put on your neck? Anyways, I've seen those for wrists. That might be a great idea. I've also seen hats with the same stuff in them.
Also, the cooling down of the body happens when moisture evaporates off the skin. So try a misting fan, but then try it without the water; run just the fan, and see how that makes you feel. The problems that people have in the humid areas are because it's humid (obviously) which means that water isn't evaporating into the air. By using the fan dry, it should help with that. Try both, see what works best for ya!