The best way to prevent illnesses such as the flu or common cold is to practice good hygiene, get the recommended vaccinations, and boost your immune system. Practicing good hygiene includes washing your hands often with soap and water, avoiding close contact with people who are sick, and avoiding touching your eyes, nose, and mouth. Getting the recommended vaccinations is important to protect yourself against certain illnesses. Additionally, eating a healthy diet, getting enough sleep, and managing stress can help boost your immune system and protect against illnesses.