Have a plan. Very important. If you have a chance in the next 2 days run to Barnes and Noble and buy the WDW Passporter 2006 and read it on the plane. It has short descriptions of all restaurants, rides, shows, hotels, etc. plus fold out maps of all the parks. Also check the park hours before you go. If you are staying On Property you can participate in Extra Magic Hours. Those are great especially in the mornings. Getting up early is SO worth it. Especially for Animal Kingdom. The earlier the safari ride the more animals you'll see. So... if AK regularly opens at 9am. Extra Magic Hours will allow it to open to Disney resort guests at 8am. This can make a real difference in animal viewing. The animals are more active in the mornings when it is not so hot.
If you haven't made any Advance Reservations and you'd like to dine at a few table-service restaurants call now! 407-WDW-DINE Try to get reservations for a few that you'd really like to try and organize your day around those. For example if you are dining at an Epcot restaurant for lunch, arrange to be at Epcot that morning or afternoon. (Lunches at all fancy restaurants are generally cheaper)
Bring ponchos!!! (avail. at Target/Wal-Mart) and waterproof sandals
Bring tons of sunblock and reapply throughout the day, bring a sunhat/cap
Again if you are staying on-property have your "mousekeeping" tips ready in $1 bills. Average is $3 per day per room.
Carpe Diem! Go ahead ride Tower of Terror! You only live once!
Best place to see characters is at Camp Minnie-Mickey in Animal Kingdom. It is never busy there.
Get park-hopper passes so you can do one park in the a.m. and one in the p.m. Splitting up your time in parks is good. I like to do a waterpark in the a.m., take a break then do a regular park in afternoon to evening. Oh, what bliss!
Try to hit one of the waterparks -- either Blizzard Beach or Typhoon Lagoon. For a newbie I'd recommend Typhoon. I NEVER considered myself a "waterpark person" and yet they have become one of my favorite parts of Disney. Picture it: floating around on a lazy river innertube with tropical music playing. Hello, HEAVEN!
The best dining is at the resort hotels. Anyone can dine there even if you are not staying there. You can even walk around the hotel lobbies/grounds and look at them. I LOVE doing this, especially at hotels I always dream of staying at! For example if you eat at Boma at Animal Kingdom Lodge, get in some FREE animal viewing on their savannah!
Visit the Boardwalk. (ride the friendship boats over, or walk from the rear entrance of Epcot) It's beautiful and fun to walk around at night. Plus great dining. Don't miss Jellyrolls!
Try a dole whip in Magic Kingdom!
Don't miss the parades or the really cool shows like Indiana Jones and Festival of the Lion King. You will appreciate getting off your feet as well.
Don't try to do everything! I know it's tempting. But remember, you're gonna have an amazing time and you'll get the WDW-Fever like the rest of us which means another trip on the horizon!!!

That's how we are at the DIS, we haven't even left and we're planning future trips!
Have an incredible trip!
stina
