Beans, pasta, rice, and eggs are big budget stretchers when you cook. You can buy them in bulk and store them, beans are as much protein as meat so you can meatless with beans. You can even toss extras in a ziploc bag and freeze the extras. You can also save extra rice and pasta. Toss cooked rice or pasta in a ziploc bag with a touch of oil or butter, then it can be microwaved for next days meal. Eggs you can use for omlettes and fritattas which are good uses for extra veggies you may have. Another way to save extra veggies is to place extras in a bowl or ziploc bag in the freezer. When the bowl or baggie is full it makes a great soup. You can save any bones from any meat you make, freeze, and use later to make broth. Drain, then this is a basis for soup. If you have leftover meats and it is a small amount, freeze it to go in soups or stews. Something like meatloaf can become tomorrow night's burritos, tacos, or chili.
Remember you pay for convience. Buy fresh veggies and fruits and cut them yourself. Bake your own breads and pastriesif you can. In some cases store brands are just as good as name brands, but that will take some experimenting to find what you like. Use coupons (the price of a Sunday paper is worth it) Find store that double or sometimes triple coupons and have rewards programs and use those. Plan your meals a bit so that you can use what is on sale for that week. Some stores now are giving you a bit of a credit if you bring in your own bags, so good canvas bags are cheap but will save you some change in the long run.
I hope this helps you. This is the way I was rasied and still do many of these to this day. Good luck
PS. There are many recipe websites that can give you great cheap recipes and tips. You just have do a bit of searching.