What to do?
Numerous public health organizations included the CDC, DHS and WHO have all issued guidance and recommendations, as have many public media organizations such as the New York Times or VOX Media. There are many suggestions as to how to proceed ranging from the simple and practical to incredibly detailed.
Here are a few of the most common:
Wash Your Hands
Make a practice of washing your hands regularly, particularly before and after meals and after being in public spaces. The above video illustrates the proper technique; note in particular that any soap will do - anti-bacterial is not necessary, and also that the water temperature is not critical. Be sure to wash vigorously for 20 seconds.
Maintain a distance of at least three feet away from anyone visibly sick. Depending on conditions in your local area, avoidance of large scale (concerts, sporting events, etc) or even small scale (grocery, restaurant, etc) venues may become necessary. It's possible that self-isolation becomes necessary for some period of time, which is why many resources recommend having non-perishable food stores on hand. A list of recommended supplies is available here.
Avoid Touching Your Face, Hands, Mouth
It is not known precisely how long the virus can survive on exposed surfaces, but health organizations consistently recommend the avoidance of touching your face. Any of your eyes, nose and mouth can provide a vector by which the virus enters the body and infects you.
Plan, Don't Panic
The COVID-19 outbreak is a serious health situation, but drastic countermeasures in China and geographies like South Korea have bought the world some time. The virus is dangerous, perhaps anomalously so, but concrete steps can be taken to mitigate the risks it poses. Careful planning about family and elder care, supplies and travel can help weather the storm.