They can be used dry - which is known as a rub - or wet, Bielunski says.
Rubs usually are used on tender meats such as strip, sirloin and rib-eye steaks.
Tougher cuts such as chuck or round steaks can be improved with a tenderizing marinade, Bielunski says.
Marinades usually consist of acid, oil and flavor components. The acidic portion breaks down muscle fibers and tenderizes the meat, while the oil coats the surface to seal in natural juices and keep the meat from drying out during cooking. Herbs and spices provide flavor.
Marinades also can add flavor to vegetables such as eggplant, zucchini and tomatoes. Kline says she uses a roasted garlic marinade before grilling firm-fleshed vegetables such as onion chunks, summer squash and partially cooked new potatoes.
If you're marinating meat and then taking it to the grill, don't use that marinade again on the finished product, says Diane Van, acting supervisor of United States Department of Agriculture's Meat and Poultry Hotline. If you plan to use marinade as a sauce on the cooked meat, set aside some of the mixture before marinating to use later, she says.
Another option is to make a second batch that hasn't come in contact with the meat, says Lynn F. Little, an extension educator in Washington County for University of Maryland's Cooperative Extension Service.
Boiling the used marinade isn't recommended because it won't kill any potential bacteria, Little says.
Mix up a batch
Make enough marinade to cover the surface of the meat. About 3/4 to 1 cup is enough for one pound of meat, according to National Pork Producers Council.
Put the meat in a zip-lock plastic bag or a glass, steel, plastic or enamel container.
A plastic bag works well because you can turn it occasionally to expose the meat to the marinade more evenly, and there's no dish to wash later, Little says.
Pierce the meat with a fork so the flavors are absorbed, she says.
Pour the marinade over the meat, then cover the container or seal the bag and refrigerate.
Never marinate at room temperature, Bielunski says.
"Busy consumers may put it on the counter and think they'll get back to it in 30 minutes, but they don't," she says. "It's a food safety issue."
Tender meats such as fish or pork tenderloin only need 30 minutes to two hours in the marinade to take on new flavors, while tougher cuts can benefit by sitting for a longer time.
National Pork Producers Council suggests that thin chops or medallions be marinated 30 minutes to two hours, cubed meats from 1 to 24 hours, thick chops from 2 to 24 hours, boneless roasts weighing 1 to 4 pounds from 12 to 24 hours and ribs from 12 to 24 hours.
Marinating meat for longer than 24 hours isn't recommended, because the fibers break down and it becomes mushy, Little says.
Some people don't like to make marinades because they have to think ahead, Bielunski says.
If you're short on time, the process doesn't have to be complicated. A jar of salsa or a bottle of salad dressing makes a quick, tasty marinade.
Fresh papaya, pineapple and ginger contain enzymes that are useful for tenderizing, Bielunski says.
The freedom to experiment is the fun part about marinades, and you won't sabotage your diet, Kline says.
Kline, a registered dietitian, says oil used in marinades adds minimal fat to the recipe, because most of the oil stays in the marinade when the meat is removed. Marinades boost flavor without adding a lot of calories, she says.
Use your imagination to come up with different variations, and don't worry about making a mistake, Kline says.
"It's really hard to go wrong," she says.