These items are typical official advice, and certainly beneficial. Currently the official stance by most health care authorities is COVID-19 spreads mainly through physical contact and respiratory droplets, as from a cough or sneeze.
If that was the case, unless someone within 3 feet sneezed in your direction, or unless you didn’t sanitize your hands, you would not get it.
However the rate of spread might possibly indicate there is some aerosol transmission, IOW micro-droplets that stay suspended in the air. This is debated but some documented cases would seem to support this. E.g, one person infected 16-18 others in the German nightclub https://postofasia.com/after-one-contaminated-16-at-berlin-nightclub-coronavirus-fears-develop/
The outbreak in New Rochelle NY started at a synagogue, where one person infected many others: Coronavirus: New York Creates 'Containment Area' Around Cluster In New Rochelle : Shots - Health News : NPR
The method of transmission is still being investigated but it seems unlikely that one person sneezed directly on 16 others. Some recent studies show a significant fraction of influenza transmission may be via aerosols. : Study confirms flu likely spreads by aerosols, not just coughs, sneezes | CIDRAP
The “basic reproduction” or R0 number of COVID-19 is maybe 2.3, vs influenza at about 1.3. This implies COVID-19 is more contagious, although not nearly like measles which has an R0 of 18.
The average incubation period of COVID-19 is about 5-6 days with some outliers to 11-14 days. This differs from influenza which averages 2 days. That means a person infected with COVID-19 and having no symptoms could contaminate others for at least 5-6 days and maybe 11 days before he became obviously ill. Before he became ill it is less likely he’d be sneezing or coughing, yet the disease is spreading rapidly.
Official recommendations say avoid “large gatherings” or “mass gatherings”. The typical definition of this is 1,000 or more people. However in the above nightclub and synagogue cases, there were far less than 1,000 people present. It would appear there’s some risk from social, religious or community gatherings where hugging, handshakes, or close physical proximity are common - maybe in groups no larger than 50.
Besides washing your hands, not touching your face and cleaning surfaces, it would help to maintain 6 ft (about 2 meters) distance between other individuals. However this is not always possible.