Washing your hands is one of the easiest ways to keep yourself safe. Wash often with soap for 20 seconds. Then dry. This kills the virus by bursting its protective bubble. You can use any temperature of water to wash your hands, as long as you use soap. Cold water and warm water both kill germs and viruses.
Coughing or sneezing into your elbow catches the droplets and stops them from getting on your hands. COVID-19 can remain on plastic and stainless steel surfaces for up to around 3 days, and less than that for other types of surfaces. This will depend on the surface. If surfaces look visibly dirty, clean them first. It is best to use a disinfectant. Use an antiviral disinfectant and follow instructions. Remember to store cleaners and disinfectants safely.