To use a meat thermometer properly, you must insert the probe into the thickest part of the meat, avoiding bones, fat, and gristle. You should also check the temperature in multiple spots to ensure even cooking. You can use a meat thermometer near the end of cooking to check for doneness or a leave-in thermometer that monitors the temperature throughout the cooking process. It would always help to clean your meat thermometer with hot water and soap before and after each use.