We always do breakfast in the room to save money, and time. My DS doesn't like pastries (like Pop Tarts or muffins) etc. so I pack cereal, plastic bowls and spoons, and buy a 1/2 gallon of milk in the gift shop.
I tried the free ice water at counter service tip, but we thought the water tasted awful. It literally tasted like the toilet water smelled.

Even flavor packets couldn't save it. So we budget in bottled water, now. YMMV (Your Mileage May Vary) as many people say it tastes fine. And I do drink tap water at home so I'm not a bottled water snob!
When we aren't on the free or discounted dining plan, we share meals to save money. There is almost always more than enough food! It's just my DS and I, so I'm not sure about your party size, etc.
Limit table service meals. They are very expensive and you have to factor in a tip as well.
During parades and shows like Fantasmic, there are carts selling glow-type toys. My DS always wants one and they are not cheap. So I bring glow toys from the Dollar Store and pull those out for him instead.
Another thing I do is buy Disney gift cards ahead of time from somewhere that gives me a discount. I buy them at Kroger which gives me fuel points. Lately I have been able to get gas for $1.00 off per gallon because of my grocery and gift card purchases. Some people do the Target discount but I don't have a Target card. Other people get them discounted at Sam's.
Limit souvenirs! That's a big one! My DS always gets a small carving from the wood carver in Animal Kingdom, and one stuffed animal. I get a magnet for our fridge collection and we buy one Christmas ornament. Other than that we don't buy a lot of souvenirs.