Take an iron nail - rusty and old. On a dark night - moonless and cloudy, set upon a smallish flat stone. With an iron hammer strike it thrice. At each stroke say:

Clavus Ferreus

Malleus Ferreus

Ferrum Refilum

Ferrum Nobilis Score the stone three times across with the nail's point, then take the stone and bury it far from the house. Carry the nail with you always as a charm.