How do you do defense against witchcraft and wizardry?

It all kind of depends on what kind of supernatural creature you're talking about.

Ghosts-ring of salt around you, line of salt againt all doors and Windows (any entrance), pure iron wards them off

Demons - ring of salt around you, line of salt againt all doors and Windows (any entrance), they flinch in the name of god (Christo), holy water

Hell Hounds - ring of salt around you, line of salt againt all doors and Windows (any entrance)

Death Echo - nothing really you can do but they will not harm you (they are simply reliving their death over and over)

Vampire - dead man's blood is like poisin to them, cutting off its head is the only sure fire way to kill them

There's more but these are the basics