According to legend, if you break a mirror you will receive 7 years of bad luck. Like many superstitions, this one has a variety of counter agents to combat the 7 years of bad luck, antidotes, if you will, for the curse.
One of the antidotes is to toss salt over your left shoulder with your right hand (this is also used if you spill salt).
Immediately after breaking the mirror, spin around 3 times counter-clockwise.
Grind the shards of the mirror into powder so that no reflections can be seen in the pieces.
Submerge the pieces of the mirror in a south-flowing stream, this will reduce the time the bad luck remains from 7 years to only 7 hours.
It's said that you can also touch a piece of the broken mirror to a tombstone to immediately lift the curse.
On July 13 the Museum of Early Trades and Crafts in Madison, New Jersey held a Friday the 13th program to explore and shed light on various superstitions.