Before you go to the grocery store, plan your menus for the week and create a grocery list to support the menus. That way the food you buy is already designated for a specific meal. This will eliminate impulse purchases and, in turn, eliminate waste.
Once you're at the store, buy what's on the list you created. If you had apples on your list, but you're just as happy with pears and pears are on sale, of course buy the pears. However, if there's a big sale on a bulk item you rarely use that isn't on your list, pass it by. It's likely you'll end up wasting more than you would save by deviating from your list.
When restocking your fridge and pantry, do what the grocery store stockers do: Move older items to the front so they are used first, and put the new purchases with a longer shelf life to the back. This way you're more likely to use food before it expires.
Fruits and veggies vary in freshness factor, so do your homework and learn the best way to store the produce you buy most often. For example, do not refrigerate potatoes; store bananas away from other fruits (like avocados and apples); and never wash berries until right before you're ready to use them. Little tips like these can add days to your purchases!
Fresh herbs can last up to 2 weeks when properly prepped and stored. To keep a few days, trim stem ends and place in a tall glass with fresh water. Change the water when it becomes cloudy. For longer storage for herbs like cilantro and parsley, wash, dry completely, then gently roll the herbs (stems on) in paper towels. Place in zip-top storage bags, expel air from the bag, and seal. Store 1-2 weeks in the refrigerator.
When it comes time to cook, prepare a realistic amount of food, and do not overcook. There's no need to prepare eight servings of short ribs if you live alone. Learn to pare down recipes to suit your family size.
To freeze your leftovers properly, cool the food to room temperature, place it in freezer-safe containers, date the containers, and label them clearly with the contents. Then add those leftover meals to your next meal plan so you are sure to use them.
Fresh fruit can be prepped and frozen in 1/2- or 1-cup portions in freezer bags and used in smoothies instead of ice. That means added nutrients and no watering down your smoothie. If you're going for a banana smoothie, don't throw away the peel! Banana peels chopped and frozen in zip-top freezer bags make a great "ice cream" type treat when blended with a little milk (dairy or dairy-free milk will work). Veggies can be diced and prepped for the freezer, too, for use in future meals.
If you have leftover coffee in the morning, you might be pouring dollars down the drain. Instead, pour cold coffee into ice cube trays and freeze. Use them later for homemade coffeehouse-style frozen drinks or iced coffee. You not only save that leftover coffee, you also cut out that high-price coffee-shop bevvy.
Leftover fruit juice can be frozen just like coffee in ice cube trays. Use the fruity cubes for smoothies, or healthier slushy drinks for the kids, or cocktails for the adults -- no ice to water down your drink!