You should apply the rub before you cook the food. This treatment allows the rub to permeate the food, adding flavor and, in some cases, texture in the form of a crisp crust. Once you've applied the rub, cover the food loosely with plastic wrap and refrigerate it for at least 30 minutes, or up to six hours, depending on the food. Apply a rub to fish or vegetables right before cooking. Season chicken an hour or two before you cook it. Larger cuts of meat can be refrigerated several hours.

How you apply the rub depends on the food you're seasoning. Spoon or sprinkle rubs over beef, chicken and pork and use your fingers to massage the seasonings into the meat. Slather a bit of oil on lean cuts before you add the rub. Fish is too delicate for this aggressive treatment. Instead, spread a bit of oil on the fish and shake a fine layer of seasonings over it. Rubs are typically reserved for meat, but they make vegetables taste delicious, too. Coat the vegetables lightly in oil. Then place the vegetables in a plastic bag with a rub and shake to coat.

Although the technique for using a rub is almost always the same -- apply the rub before cooking -- rubs themselves come in many variations. Start with a bit of sugar or salt and add various flavors. Chilies and paprika provide heat and smokiness. Thyme, rosemary or lavender add an herbal flavor. Citrus zest brings a bright spark of freshness. When making a rub, consider the character of the meat you're using. Beef and fish need a rub that's on the salty side, while poultry and pork benefit from a bit of brown sugar in the rub. Too much sugar can cause the meat to caramelize and burn. For lean meats, you can make a wet rub from oil and a concentration of spices or inject the meat with a salt or sugar solution.

When using a rub, keep all surfaces and equipment clean and keep raw foods separate from cooked foods. Wash your hands with warm, soapy water immediately after massaging the rub into the meat so you don't transfer bacteria to kitchen surfaces or other foods. As you massage the rub into the food, some of it will inevitably fall off the food. Don't reuse this leftover rub. Don't use a rub directly out of a container, but pour what you need into a bowl to prevent contamination. Discard any rub that may have come in contact with raw food.