When waiting for an elevator, leave the area if someone makes you feel uncomfortable.
 
Check the elevator mirror before entering.
 
Stand between the control panel and door when in the elevator
 
Exit the elevator if someone enters that makes you feel uneasy. If you feel the need to give an excuse you can say "Oh, I forgot my mail."
 
If accosted, press as many buttons as possible to try and get the elevator to stop at the next floor.