Preventing 

Mask are good, N95s are better.
Wet/damp masks are not effective.
Always mask indoors when not at home.
Only close friends can be trusted to report sickness, and assume they are asymptomatic when they appear well.
Assume ALL illnesses not positively identified are COVID.
Increase airflow in spaces you can effect.
Provide air filters for spaces you control.
If people can't hear you through your mask, find a quieter space.