It may sound obvious, but you could start by buying less food. You’re better off making trips to the market more often and coming home with one bag of groceries (as opposed to several).
Don’t be tempted to buy food in bulk, just because the price is right. Unless you have an enormous amount of storage space in your home, most of this food will go to waste. Let’s use bananas as an example: even if the market sells bananas in large bunches, it’s perfectly fine to pull one or two bananas off the bunch and just buy those ones.
How about the rest of the fresh produce you buy? Does much of it end up rotting in a refrigerator door before you get around to eating it? This could be a case of “out of sight, out of mind.” As soon as you get home from the market, display your fruit and vegetables in an attractive bowl on the kitchen table or one of those mesh, metal baskets that hang from the ceiling. The produce will not only brighten the room but serve as a reminder to eat it.
As soon as you get home from the market, separate meat into individual servings (i.e. one chicken breast or 4 oz. of ground beef) and put each serving in a separate freezer bag. Mark the freezer bag with a Sharpie marker with the date. Put all the servings in the freezer except one, which you can put in the main part of your fridge, as a reminder to eat it that night for dinner. Then, when you’ve used that serving, you can pull one more out of the freezer to defrost for the next day.
When you’re cooking, cut recipes in half or put leftovers in air-tight food containers at once. Plastic wrap and tinfoil are less reliable than containers that snap shut. Individual-sized Tupperware-style containers can go in the freezer, too, so you can take one out at a time to reheat in the microwave.
Store dry goods in lidded jars. If you’re worried that you’ll forget the cooking directions (for rice or pasta, e.g.) then cut out the cooking directions from the original packaging and slip that in the glass jar where it’s easy to read.