Cheese is expensive and the price only goes higher when it's sliced and shredded for you. Instead of paying more for the extra processing, do the work yourself. Buy a large block of cheese, shred what you need, and slice the rest. Freeze any you don't plan to use right away and you'll have sliced and shredded cheese at your fingertips for less money (and packaging) than buying it pre-cut.
Salad dressing is another item that can get pricey, especially if everyone in your family likes different kinds. But salad dressing is one of the easiest things to make yourself, and you probably have everything you need on hand. Combine olive oil and vinegar (white, red, balsamic, take your pick) for a base, then add spices to taste. To remove the guesswork, a clever bottle meant for salad dressings ($6.50 on Amazon) has recipes printed on the side.
The price markup for pre-washed and pre-cut lettuce is substantial. Instead, buy a head of lettuce or a couple of romaine hearts and wash and cut them yourself. If you want to have cut lettuce on hand in the fridge, store the cut pieces in a container with a dry paper towel. The towel will absorb moisture and keep the lettuce fresh longer. Change the paper towel every few days as needed.
Get more juice out of citrus fruit by rolling it on a hard surface before cutting it open. For example, if fresh lemon juice is needed for salad dressing or for a delicious lemonade, roll the lemon firmly on a cutting board or counter before cutting -- and expect almost twice the juice.
Cooking spray is largely a waste of money and may contain ingredients you don't want in your food anyway. Eliminate the cost by skipping it altogether. Cooks can use olive oil, butter, or coconut oil in its place depending on the dish. Coconut oil works especially well for baked goods to keep them from sticking.
Ever tried to make a recipe with brown sugar only to discover it's hard as a rock in the cupboard? Next time put a few marshmallows in the brown sugar to keep it soft when storing.
Most recipes call for no more than a few tablespoons of fresh herbs, but they are sold in bigger bunches and often the unused portions go to waste. Instead of tossing them, cut them all up and freeze what you don't use in ice cube trays with water. The cubes can then be tossed into soups and stews, or mixed with butter for sautéing vegetables and meats.
Homemade guacamole can go brown fast. Prevent discoloration by retaining the avocado seed and placing it in the guacamole until it's ready to eat. This trick won't keep it fresh forever, but it will keep guacamole greener for hours longer and is especially helpful when taking the dish to a party. Store unused avocado with a slice of onion to keep it fresh longer.
Warming up leftovers in the microwave can leave them dried out and inedible, so before nuking a meal, add some moisture. Sandwiches or other foods with bread will turn out better if they're wrapped with a damp paper towel before they're reheated. If it's pasta or meat, place a glass of water in the microwave along with the dish to help keep it moist.