Use the freezer. I freeze -
* leftovers, in plastic containers, labelled. I often deliberately cook large casseroles in order to have leftovers to freeze.
* sliced bread. We bake our own (another saving) and slice it. One loaf gets left out for those who reckon frozen bread just isn't the same even when thawed; the other loaf gets frozen for those who know better. If I need croutons I make them fresh from the unfrozen loaf.
* grated cheese. I buy it already grated (about the same price) and keep frozen parmesan, frozen cheddar and frozen mozzarella, all grated and each in its own bag. I use it frozen, if I need it thawed I just get it out a bit earlier.
* bulk meat. We buy a whole sheep at a time, or a whole rump, sliced, because it's cheaper than buying it piecemeal.
* fruit. Some fruit tastes great when frozen and is a great thirst quencher. You can also make frozen smoothies which you can eat with a spoon - like sorbet, only easier, cheaper and healthier.
A frozen lemon or lime can be zested while frozen, then refrozen for the juice later (thaw in microwave for juice).
* prawns. I keep frozen prawns because when you cook them up they taste fresh and can make a fairly ordinary meal seem luxurious. A prawn omelette for breakfast? With a pinch of fresh coriander leaf, maybe some freshly picked shallots and parsley? Fabulous! And if the eggs came from our own chooks...
Other cost-cutting tips - I grow my own herbs, make my own herb blends. I dry bunches of herbs hanging from the ceiling and keep then dried, ground or whole leaf in jars ready for use. Some herbs don't dry well, so I make them into sauces (such as making basil into pesto, or tarragon into bearnaise) and freeze the sauce. Or you can chop the herbs fresh and freeze them.
We try to grow our own vegetables but simply can't grow enough. Still, it's good to have some, to help add a bit and to have something really fresh. It's also been good to teach the kids to appreciate really fresh, home-grown food.
Meat - when cooking a beef stew, I use the absolute cheapest cut I can get - gravy beef - and cook it on a slow simmer (so the surface is barely moving) for three hours. It tastes fabulous. I've done the same with mutton (especially for Indian curries).
For stir-fries, I freeze the meat until it's firm, then slice it while still frozen. It gives much thinner slices and makes it easier to take up marinade flavours fast. This works equally well for chicken, beef or pork.
A low budget beef stir-fry tip - use whatever cheap steak, don't worry about only buying rump or fillet. This works for blade, topside, round - whatever. Slice it thinly and soak the meat slices in 1 teaspoon bicarb soda mixed with 1 Tablespoon warm water (not so warm it fizzes). Only soak for half an hour or so, then rise it (to get rid of the sodium) and marinate again in whatever you want. or just stir-fry from there. It will be as tender as fillet.
I also have a number of recipes which follow on from each other. A roast chook (chicken) one night, chicken sandwiches next day for lunch, chicken caesar salad as an alternative, then chicken supreme (our kids love it) for dinner. With what's left I make chicken stock which I can use to freeze (and make the next lot of chicken supreme) or make risotto, or chicken soup, or chicken and corn soup.
I think it's important, whatever you choose to do, to stick with it and follow through. There's no sense in cooking enough to have leftovers if nobody eats the leftovers or puts them in the freezer. But if you plan, and check the fridge before you give up and open a packet of something, you can often throw a meal together with what you already have.
Anyway, that's just a few ideas which should translate OK from across the Pacific...
Marg