I'm currently writing a novel as well, about supernatural creatures and mythology. Ghosts are actually quite tricky to stop in "real" mythology. You can, of course, try to put their spirit to rest, by completing the pattern of the ghost or breaking the pattern. You see, ghosts are forced to follow a pattern, like killing people for a certain reason (race, territory, looks...).
There ARE however a lot of different apotropaics for ghosts. Iron, silver, salt (symbol of purity), obsidian and chalcedony are all supposed to make a ghost go away. In modern fiction, like the tv show Supernatural, shotguns loaded with rock salt rounds can hurt a ghost. Iron rods being stabbed in a dead person's remains is said to work as well.
You can, however, use other methods. You can create symbols on the ground to catch a ghost or even do a ritual. It is all about the ideas of an author to use the mythology and turn it into something special.
Good luck.