Don't force characters on young children. Many children who talk nonstop about wanting to meet Donald are totally intimidated when they see a giant duck. If they seem shy, watch from a distance and allow the child the chance to see the character interact with other children. If they're still not interested, find something else to do. Other children love the characters and want to meet them all. Make sure you have an autograph book and a thick pen ready. Don't be upset if your child would rather meet characters than spend time waiting in line at other attractions. Check your park map for times and meeting places. Character dining also offers a great opportunity to meet characters, and allows for a little more interaction with them.
The shows at Walt Disney World are all family friendly. Remember, though, that some of them have loud noises or periods of darkness. Sit toward the back so if you need to make a quick getaway you won't be disturbing others. Remind your children that the shows are make believe. It's heartbreaking to hear a young child crying during Fantasmic! because they think that Mickey is in trouble.
Familiarize yourself with the height guidelines for the rides. Measure your child before you leave so you'll have an idea of which rides are and aren't suitable. Remember that the height regulations are there for safety reasons, don't buy lifts to put in your child's shoes to make him or her taller. For rides that your child isn't taking, take advantage of the "rider swap" system. It allows one parent to ride, then they swap places so the other parent can ride without having to wait in line. Ask a cast member at the ride for details. Many of the kids favorite rides are also FASTPASS attractions; a system that allows you to swipe your ticket at select rides for a pass that will allow you to come back at a certain time with little wait. One word of warning; Dumbo the Flying Elephant is not a FASTPASS ride and the lines grow long quickly, so you might want to ride early.
Take a break during the day. Head back to the hotel for a snack and a nap, or ask a cast member for suggestions for a quiet spot where your child can sleep in the stroller. There are also "Baby Care Centers" located in all four theme parks.