Take the disposable emergency ponchos w/ you into the parks each day. It will probably rain at some time.
Slow down and smell the roses.
Drink lots of water. You can ask for a cup of ice water for free at any of the CS restaurants.
Don't forget your sunscreen and a hat.
Study a good guide book or two. Public libraries usually have some. One of the best and most comprehensive is the Unofficial Guide to WDW.
You cannot possibly do Everything in one trip. Make a list of the "Must Do's" and do them.
Gleen as much info as you can from here and at
www.allearsnet.com.
Take a break in the afternoon. Wash feet and change socks at that time. Watch for blisters and hot spots. If you don't have bandaids / moleskin, the first aid stations do. Happy feet make for a happy vacation
Let the slowest one in your party set the pace. Let the kids choose which rides to ride first.
Get plenty of rest. If you cannot make an early morning EMH or a late night show, it is OK. Save it for another day when all are better rested. Do not try to do an early morning after a late night.
Drink lots of water.
And most importantly...Have FUN.