Use your reward points to get free food. You don’t need any of that stuff in the rewards catalog (well, maybe the movie passes), but you need food. And it usually takes way fewer points than the rewards.
Make a document with a list of items you typically shop for, print it out each week and keep it where you can circle things as you run out of them. This not only ensures everything gets onto the list, it gives you an idea how much you buy every week.
Try the store brand version of one item every week. They won’t all be just as good as the more expensive brands, but you’ll probably find several that are.
Shop wholesale clubs only for things you’re going to use steadily — otherwise it’s wasteful. (I still feel bad about the gallon of salsa I once bought at one of those places.)
Buy small packages of junk food in bulk. Then, of course, you’ll have to lock them away from the kids. But if you take these along on family outings, you’ll be paying only a fraction of what they would’ve cost individually at a convenience store. This also works for juice boxes and canned soft drinks.
Make your own lunch meat. Cut cold roasts into thin slices with a slicing machine — sliced meat costs twice as much as unsliced. Or make ham or chicken salad in your food processor.
Stop buying paper napkins. Use paper towels or cloth napkins, or make your own out of an old disposable tablecloth (the kind that have felt on one side, plastic on the other — just don’t put them in the dryer).