#1 tip, don't eat at the parks if you can help it.
#2 tip, stay at a time share/condo so you can use tip #1 to the fullest.
#3 tip, eat at restaurants off property if you can.
#4 tip, If you have to eat at the parks, share a meal. 1 adult meal should feed 2 small children.
#5 tip, buy an Orlando Zoo book before going - it should contain useful discount coupons.
#6 tip, see if any saver club you are a member of offers Orlando discounts, such a AAA
#7 tip, plan each day to do LESS than you want. Don't expect to see it all. You will have more fun and spend less money if you take a relaxed approach.
#8 tip, Plan a day at Universal Studios Islands of Adventure - buy a fast pass if it is busy. If your time is limited, it is worth it to pay to cut in line.
I've been to Disneyworld many times. Food is overpriced. If you are staying at a time-share or condo, try to eat there as much as possible. Eat a big breakfast before heading to the parks. Take a break in the heat of the day and leave the parks to relax and get some food. Eat a late lunch or early dinner then head back later.
I believe that you should be able to take bottled water with you into the parks. Make sure beforehand, but if you still can, do. Pack a cooler in the trunk of the vehicle and fill it with ice/water/snacks. The money you save on food/snacks can be well spent on other activities.
The parking lots at all of the parks are huge. Try to get there super early for a spot close so it makes it easier to walk back to the car. The only exception to this is the Magic Kingdom. At that park it pays to get a locker so you don't have to carry your stuff all around the park.