If you get there when they open and are trying to avoid crowds, then my suggestion is to hit the most popluar attractions first and get them done, because more than likely, they will be packed later on in the day. If you get the Park Hopper option for your tickets, then what you don't get done one day, you can always go back.
I will tell you the ride we waited the longest for was Peter Pan..for some reason that ride is always packed!
Have a magical trip!