Start packing (you too chb!), then the night before, remove 3 articles of clothing from your suitcase. Unless you're going on a second honeymoon and you want your mate to relive those days when you first fell in love, a few t shirts, some shorts, bathing suit and rain gear, and a soft not easily wrinkled clingy dress or skirt and comfortable shoes or sandals you've worn before, will suffice. I'm a habitual over packer and the first time I went to WDW I wore about 1/4 of the outfits I took. We were all over the place and I didnt have the time for multiple costume changes.
If you're driving, don't make yourself crazy, there's a
Walmart not too far away where you can get anything (including cheaper Disney T-shirts).
We always made lunch our major meal and did pizza, salads or burgers our dinner. It really saved $$$. And don't be embarrassed to share meals with children or light eating adults, some of the portions are huge and such a waste since you're hardly going to carry around a doggie bag in WDW.
Most of all, be prepared to not follow your plans if you find something you'd rather do. Take the time to look at your surroundings. But do rise early if you can, to get to the parks. If you get on your "must rides" first you can then wander and look at details.
Enjoy, Enjoy, Enjoy!