Some tips I can offer are:
Order ice water (if desired add mio, crystal light etc) to save on beverages
Share if possible (many places offer at least one entree large enough to do so for light to moderate appetite people)
Bring non perishable and portable snacks with you to help between meals (granola bars, trail mix, pepperoni sticks, apples, oranges, bananas, raisins, other dried fruit, fruit cups, fruit snacks, fruit roll ups, muffins, applesauce cups, cereal bars, rice krispie treats, cookies, dry cereal, chips, cheesies, crackers, etc)
Look up menu info on AllEars and check out budget friendly entrees and ones that will give you the most bang for your buck
Find the Confirmed Snack thread for the Dining Plan (it often has snack items listed with prices that don't show up on AllEars)
Eat outside that parks when possible (if you can't/don't wish to go "off campus", then even trying to eat at the Disney resorts can often result in more bang for your buck between the food courts and the "grocery" areas found in most shopping areas of the hotels
Order a pizza to the room (can find deals from offsite, but also most food courts have a large cheese pizza for about $18 which would feed 2 people over 2 meals at least!)
Earl of Sandwich is a great value at DTD
Ice cream for dinner (or lunch, we generally do this once each vacation and a sundae or milkshake can be surprisingly filling)
And finally...
They are a bit old, but the posts at the bottom of my signature about dining on $40 or $50 a day might be worth a look to see how people eat on a budget!
Good luck and I hope you have a great trip!!