Choosing a Name
It is traditional to choose a name when entering the Craft. This needs to be a name that you feel is completely you (especially, magickally speaking). It is not necessary that it match your birth number, that is a preference left up to individuals. In some cases, if a candidate for initiation does not pick a name, the initiator may choose one, under the guidance of the gods, of course.
A Craft name is a symbol of your re-birth into the Craft. It is a sign of all you are and all you aspire to be, so think on it carefully. There are some Witches who keep their name secret, revealing it only to coven-mates or other trusted Witch friends (because many believe that to know someone's true name is to have power over them). There are others who openly use their Craft name among the general Pagan populace. There are still others who take two different names, a private Craft name and a public one (Inner Circle and Outer Circle names).
One of the origins of taking a new name, according to Craft lore, was to ensure secrecy and safety. If no one in the coven knew anyone else's true name, it made it impossible to betray them to the Witch-finders.