If you spend any time in Italy, and you want to begin to endear yourself to the people here, you’d better familiarize yourself with the art of Italian greetings and goodbyes.
Don’t abuse “Ciao”.
This is one the biggest missteps Americans make when they come to Italy, blithely tossing out “Ciao” everywhere when greeting an Italian or saying goodbye. Most people will acknowledge you, but you might as well have “unenlightened foreigner” stamped on your forehead. My partner, who is Italian (born and bred here in Italy,) has helped me embrace a few important guidelines for when saying hello and goodbye.
“Ciao” is a greeting or a goodbye used for people with whom you have a familiar relationship. Don’t use it with strangers. “Salve” is the polite way to address people you are meeting for the first time. I don’t usually make the switch to “Ciao” unless the other person does so first. It’s kind of like them saying “It’s okay to be a bit more casual.”
As for saying goodbye to someone you don’t know, always use “arrivederci”. I know, it’s a mouthful, and you may stumble over rolling your r’s, but practice, practice, practice.