Pack your lunches in a cooler. Disney allows soft sided coolers to be brought into the parks but they can not contain any alcohol or glass bottles. *Baby food is allowed in a glass jar* Please note that straws of any kind are not allowed in Animal Kingdom. My kids love Lunchables and they are great for on the go lunches. I also pack at least 2 juice boxes per child. The heat in Florida can really get to children so be sure to pack plenty to drink. I also pack a sippy cup and fill it with water throughout the day. Pack plenty of snacks too. I create a fun Disney themed snack mix in a sealed container prior to leaving for Disney World. Each child gets 1 container which contains goldfish, cheerio's or fruit loops, a few Mickey fruit snacks, m&m's and raisins.
Order from the children's menu. The kid's meal portions fill me up and at half the price you can't beat it! I have a 4 year old toddler and a 2 year old and they are not the best eater's, so when we are at Disney they always share a quick service kids meal.
Ask for a free cup of water available at most quick service locations. No need to drink from the water fountain all day.
Share a fun snack with your kids. Snacks can get expensive especially if you have more than one child. We usually order a cupcake at Starring Rolls in Hollywood Studios and split it between the 3 kids. These cupcakes are huge and extremely rich so it is best to split.
Avoid eating at the buffet restaurants. Chances are if you have a toddler he or she will not eat enough to justify a $20+ childs buffet cost. Now unless this is a special buffett such as Chef Mickey's then I would say avoid it like the plague. All you can eat buffets really add up for the average family of 4. You could eat 2 dinners at quick services or even a non buffet restaurant for the cost of 1 dinner at the buffet restaurant.