>>10957736Multiple flashlights if you're going at night. I suggest investing in a cheap LED lantern that you can keep clipped to your belt loop at all times.
Never go anywhere without a knife. But just a pocket knife. Or if you have a concealed carry permit, that helps. But if you don't, seriously, don't carry a weapon bigger than a pocket knife. Cops don't like that shit. It looks suspicious.
Cameras, extra batteries, extra SD cards, Make sure you learn how to take long exposure night shots with whatever camera you have. A tripod is almost necessary for these shots, though. Camera's also help if you run into the police, because then you just look like a curious ghost hunter vs. some vandal or thief. I recommend also carrying a video camera. That way you can set it up somewhere and leave, as well as pick up audio.
Taking a friend is always recommended in my book. Helps to confirm anything you see or feel, and provide backup if anything happens.
DO NOT STEAL OR VANDALIZE. If a cop finds you there and all you have are cameras and flashlights, they will 99% of the time just tell you to leave if it's an abandoned property. If a cop finds you there with stuff newly broken, stolen stuff shoved in your pockets, or spray paint, you're probably spending the night in jail, or at least paying a nice fine.
Also, don't get your hopes up too much. Expect nothing, because when you start to expect activity, your mind is more likely to make up stuff to fill in your expectations. Don't get disappointed if nothing happens. And always keep your eyes and ears open for anything that seems out of place.
If anything disturbs you, or doesn't set right, don't be afraid to leave or call the police.
Common sense, above all else. The easiest explanation is almost always the correct explanation.