A very good defense against ghosts, and I don’t think many people have explored this, is being naked. Think about it. How many ghosts stories include the words “while I was naked,” or variations thereof? I’ve only heard of one such case, and that was a dwarf ghost that haunted this hotel room and liked to watch couples have sex. Perhaps it would be best to clarify then, that nakedness is an excellent defense against ghosts, unless of course you are dealing with a perverted ghost. For that, I can offer you no other words of advice other than to be careful about where and when you get naked.
In addition, nakedness can also be a very good defense against lots of other things, like some people and skittish creatures.