Living in a haunted house.

I don't know if there is really a trick, but it helps to not have normal career responsibilities or at least working at night. If you sleep during the day there is a good chance you will be fine in my experience and I nearly exclusively play in haunted houses anymore. I'd also try to have at least one skilled medium in the household, if possible. An investigator is even better, but I would have the hand control thing, too, just to adjust things. Don't be afraid to abuse Guidry or Bonehilda's help either.

I also remember from the guru information that large lots spread out the activity, so it feels like more in smaller lots just because it is concentrated. I have activity in both large and small lots, but I definitely find more things I have to destroy in smaller lots. I am probably over looking them in the large lots.

If there is one personal tip I struggled with... If you start losing control of your home, ban visitors on the door. I was doing the extreme haunting and my medium was constantly interrupted during the ceremonies so I had to recover standing with the spectors. In the meantime, though, my extended family decided to constantly visit and they were set on fire every time. (Interrupting the ceremonies again!) And it was like clockwork. Start ceremony; visit; fire; interrupt ceremony; put out fire; dismiss visitor; start ceremony; visit; rinse and repeat three times before I banned visitors. Oh, and don't give out keys for the same reason. I had because they were my Sims' parents.