Prevention Methods

The people of the Medieval Ages were uneducated about diseases and cleanliness. Many thought it was caught through the air, so they would burn incense like juniper and rosemary to try to prevent infected air. People would dunk their handkerchiefs in aromatic oils to cover their nose and mouth from the air. Another common remedy was the cure of sound. Church bells would ring to ward off the plague. Church bells were often rang during a crisis, so they felt this was a justifiable remedy. Sometimes cannons were fired because they were so loud. Local apothecaries made a lot of money off people during the plague years by selling and marketing all sorts of talismans, charms, and spells for protection.
Pope Clement VI, fearing for his safety, had the idea to sit between two large fires to keep the air pure. The plague bacteria is actually killed by heat, so this was actually a good method.
A few cities like Milan and Venice actually quarantined the sick. They blocked up houses of infected people, and kept healthy people seperate. They also made ships coming into the harbor not come ashore for forty days, just to make sure there were no plague outbreaks aboard. That is where the word quarantine comes from because quaranta giorni means forty days in Italian.