Simple things that we all know, but sometimes fail to due for convenience, peer pressure and who knows what else. Like buying dry goods in bulk, cooking whole grains like brown rice over white for more nutrient bang for buck and the classic using dry beans. Dry beans, are supper cheap and if you plan a little or even cook a bunch on a day off and freeze for later, the can save you loads.
Buy dry goods in bulk. Again, don't go over bored and make sure you have lidded containers to store them away from moisture and bugs.
some other tips and tricks I often use when I need to save money and still eat well which may or may not be obvious.
Jarred sauces, stocks, soups, condiments and whatever else, they aren't cheap. In fact, most are pricer than making things yourself. Which you likely know, but hey everyone loves the convenience and ease of opening a jar, so my only tip here is to use all you buy. You're going to be recycling the bottles anyway, which means you have to rinse them.
Rinse and save: Whenever I use the last bit of tomato sauce, tomato juice, salsa, veggie broth /whatever it may be, take a small amount of hot water into the bottle. Close the lid and shake to get out every last bit of content, and add this diluted mixture to whatever it was you were making. The small amount of water won't hurt. I do this with ketchup, soymilk and well everything.
Another point, with leftovers EAT THEM! Sure the same food in a row might not be super exciting but you can recycle these too.
Diluting purees/blended soups: If you make a blended soup, make it stretch and change it into something different by adding liquid of choice.
E.g.: I made corn chowder the other day and for lunch today I took out a cup of the thick blended goodness and added it to a soup pot with a bottle of V8 (using the water/rinse trick too) and cooked until combined with stirring. Now this trick would be better with a vegetable soup, but it's still good with the corn chowder. Sure it's still soup, but now its a lighter vegetable soup. This is also great if your feeding more people.
Freezing vegetable ends. Whenever you chopping or dicing vegetables save all those skins, end pieces, stalks or anything else you would usually compost and freeze them into a plastic bag. Then when your bag is full use the odds and ends to make a flavorful and tasty stock.
More on recycling leftovers
Burgers: Just about any leftover can be made into patties or burgers by adding breadcrumbs, cracker crumbs, corn flour, regular flour or some kind of grain and maybe a binding agent. Beans and rice make great burgers just smash with a potato masher and add crumbs as needed to form patties. Soups particularly the thicker kinds can be transformed into burgers in the same way, as can casseroles, chillies, stews, pasta dishes and even braised/roasted vegetables.
Casseroles: Like burgers casseroles can be made out of almost anything. Grains, veggies, legumes, burgers, soups, anything can be made into a casserole. Depending on what it is, you could add some grains , broken crackers or mashed potatoes, some gravy or sauce and you have an instant casserole. Again this is a good way to use up leftovers or if your simply stuck on what to make for dinner. Generally a starch, sauce, veggie or protein (or both!) and your half way there.
Burritos: Basically take anything you have in your fridge and add it to a tortilla and viola, instant burrito. Rice and bean dishes or curries are particularly good served this way but most any left over will do. Vegetable stir fry or sloppy vegans or chilli even your burgers can be added with some lettuce for easy transport and a tasty lunch the next day.
Bulking up: If your making soups, stews, gumbo, sauce or really anything that you feel could do with a little more adding grains is an easy and simple way to make dishes stretch further and feel more filling. Same with blending cooked veggies to add to sauces, spreads, soups or anything you fancy. This adds flavor, nutrients and bulk. The same can be done with beans, once cooked simply blend and add to anything you like.
Mashed potatoes: another cheap and easy solution. Can become a meal in and of itself with the addition of blended white beans and blended steamed greens. Or added to sauce, stews, soups etc to thicken and bulk. It can also turn most leftovers into a burger or casserole and makes a great burrito or breakfast patty if friend with veggies.
So go out and eat something!