Shop supermarkets strategically.
In addition to purchasing in-season produce, you can save by taking advantage of sales at individual grocery stores. Make your list, then check apps such as Flipp or Grocery Pal to see the circulars and sales at participating supermarkets and big-box stores in your area. Some stores require you to be a loyalty club member for the most savings, so load your membership info into the Key Ring app for easy access.

Build your menu around bargains.
Look for a “manager markdown” in your supermarket, where the staff reduces prices on soon-to-expire items. These are often done at the store level, so they don’t appear in the circulars, but discounts can run up to 70 percent off, says budget consultant Andrea Woroch.

… and ask your guests to help.
Casual summer parties, picnics and barbecues work great as potlucks. Use a site such as PerfectPotluck.com or SignupGenius.com to coordinate who is bringing what, and to limit overlap. Guests who don’t want to cook can sign up to bring paper plates or utensils.

Stock up on summer decor right after Memorial Day.
The party supplies that go on sale after Memorial Day—cups, paper plates, plastic utensils and so on—will work just as well for Independence Day and Labor Day parties later in the summer season, says Kimberly Palmer, a spokesperson for personal finance website NerdWallet. Look for clearance sales on such items at grocery stores, party-supply stores and dollar stores.

Buy your booze at a warehouse club—even without a membership.
You don’t have to join to save. Nonmembers can access the discounted prices on alcoholic beverages at BJ’s and Sam’s Club, and the savings can be significant. At Costco, the rules vary by state, so check your local outlet’s website to see if you can save.

Skip single-serving drinks.
Canned and individually bottled soda and water can get expensive. Skip them and instead make a punch (with or without alcohol) or lemonade, and put out a large pitcher filled with ice water and slices of lemon or lime. “People always think that’s fancy, and it’s basically free,” says Hannah Rinaldi, who runs the blog EatDrinkandSaveMoney.com.

Get creative with leftovers.
Making leftovers more appetizing means you’re more likely to eat them, saving you the cash you would have spent on subsequent meals. The key is to create dishes that don’t make you feel like you’re eating the same thing every day. For example, leftover patties can go into a pasta dish or cheeseburger salad, while pork shoulder can become a taco filling.