Most of my hints have been mentioned all ready.
1st and foremost. DVC. Stay in studios. Get some food from garden grocer or stop at a store.
Annual Passes (again DVC helps with a $100 discount.)
When you go often you do not feel the need to "do it all" or go all out. We reuse our souvenirs. We bring back the kids ones the most. Hat's, light spinners, T. Shirts,pins, the whole thing. We normally get something new for each person each trip. We look like we spent a lot, but many of these things we have been collecting for years. If we have a car we love to go to the outlet store too.
If the girls want to wear costumes they bring ones I bought on clearance from the
Disney store after Halloween. We have lots. No $175 per child at Bibbity Boppity for us.
The dinning plan with DVC is great. you can get it, with out having to pay rack rates or buy tickets. If you don't get it, you can spilt meals and that counts down on the price of things.
This past trip was about $700 in food and souvenirs and $500 for airfare for a family of 4. We had about $300 of reward points on our Disney Visa too. The tickets were AP and DVC was the room.
We are taking 3 trips to WDW this year. After that we have to cut down, we can't keep taking the kids out of school so much.
Cheap airfare. We keep looking, and get deals. We almost always pay less then $100 per ticket each way. Sometimes much less. It helps that going to Detroit to Orlando are popular flights and there are a lot. Right now there are 3 airlines that do non stop (maybe 4 if you fly out of flint.) This keeps the prices competitive. Both SW and Spirit can have some great internet deals if you keep your eyes open.
Not renting a car can save a lot. Even then sometimes we can find some good deals online too.