A segulah is an action that is reputed to lead to a change in one’s fortunes. For instance, acting as the kvatter (the one who brings the baby into the brit milah/circumcision) is purported to be a segulah for fertility. Or, wearing the jewelry of the bride while she is under the chupah is said to be a segulah for finding a husband. There are also special segulot related to prayer. Reciting the Song of Songs daily for 40 days, or praying at the Western Wall every day for 40 days is reputed to “shake the rafters” of Heaven, increasing the likelihood of a favorable response.
The word segulah might be translated as a spiritual remedy or an auspicious tradition. In the Bible, however, it is used in the phrase Am Segulah, a treasured nation (Exodus 19:5; Deuteronomy 7:6, 14:2, 26:18), and refers to the special relationship God has with the Jewish people.
Perhaps then, a segulah might be understood to be an action that demonstrates a treasured relationship with God by doing something extra. In the case of praying or reciting the Song of Songs for 40 days, this makes immediate sense. But what about the case of the kvatter or the single woman and the bride’s jewelry as mentioned above?
In these cases, the "treasure" that is being dedicated is joy. A person who longs to be married might feel personally sad attending someone else’s wedding. Holding a piece of the bride’s jewelry, however, can help a person refocus thoughts both on the joy of the bride and groom and toward an optimism about her own future (and the same for the kvatter).
One can certainly find an abundance of segulot. And while some have a strong basis in tradition, others are old wives’ tales--and the rest fall somewhere in between. In choosing to do any segulah, be certain to check that it has a source in Jewish tradition, and always remember that the most important purpose of the segulah is drawing closer to the Divine, and not just changing one’s situation.