Plan to have your food finish cooking just as you're ready to leave home. Just before leaving, take the food from the oven or stove top.
Depending on the type of food, you may want to transfer it to an electric slow crockery cooker for extra insulation. These are perfect containers for soups, stews, and some casseroles.
Wrap the covered dish, container, or crockery cooker in several layers of newspaper or a heavy towel. Place in an insulated cooler for transport. The food should stay hot for up to two hours. If you are using an electric crockery cooker, plug it in when you arrive at your destination and the food will keep warm on the low-heat setting for hours.
If you're toting a salad or a cold appetizer, you'll want to be sure to keep the food well-chilled. Chill a clean cooler by filling it with ice for at least 30 minutes before packing. Have the foods thoroughly chilled. Pack the food into the cooler just before leaving home.
Whether you brought a hot or cold dish, discard any leftovers that have been left at room temperature for more than 2 hours.