Meats are one of the most popular items to make in a slow cooker, but they need to be thawed beforehand or they'll take too long to cook. When cooking meat, it's important to heat the meat to 140 degrees Fahrenheit (60 degrees Celsius) as quickly as possible to kill any bacteria. Always make sure the internal temperature of the meat is within recommended guidelines before serving. When cooking poultry, use poultry with the skin still attached -- this will help keep the meat moist throughout the cooking process.
Prepping vegetables for slow cooking may take longer to prepare than the meat -- it's important to cut them uniformly so they'll cook evenly. Vegetables may also take longer to cook than meat, so when preparing stews or meat-and-vegetable dishes, layer the vegetables on the bottom of the pot.
Some of the best slow cooker meals are soups and stews because the slow cooker is designed to simmer on the low setting for long periods of time. Cover soup ingredients with water, and if you need to add more liquid during cooking, bring it to a boil first, so it doesn't lower the soup's cooking temperature.
Dips and spreads are another category where slow cookers shine. The low heat keeps a cheese-based dip warm without burning the ingredients, and maintaining a dip at a low heat prevents ingredients from congealing during a party.
Grains are sometimes a surprising way to use a slow cooker. Oatmeal, cracked wheat and rice porridge can be cooked overnight to provide a hot, nutritious breakfast. Bread and bread-based dishes like stuffing can also be baked in a slow cooker -- the low heat setting also helps bread dough rise. Another surprising slow-cooking category is desserts. While rice and tapioca puddings may seem like a no-brainer, you can also use slow cookers to make hot fruit desserts and even cakes.
Some recipes call for adding ingredients near the end of the cooking time because of the nature of the ingredients and their tolerance for the slow-cooking process. Spices and herbs may become too concentrated during cooking, so be sure to adjust their levels at the end of the process. Likewise, some vegetables, dairy products and seafood will lose their flavor and texture if simmered for too long, so if the recipe calls for including them near the end of the process, be sure to follow the directions carefully.