Get a priest or minister or rabbi or someone similar in to do a house blessing. Keep a "Bridget's Cross" in it. Sprinkle salt across the outside of all the doors and windows, or place horseshoe nails there. "Tell the house" that you are the owners and will do your best for it.

These are all old-time recipes I found looking in some of the books I have. I assume you don't want to do things like burning feces in the stove.