Ghost hunting is a interesting, intriguing, enjoyable experience that can expand our understanding of the paranormal realm. Exploring haunted locales and dark cemeteries as dusk falls, then turns into pitch black night, is a serious adrenaline rush; and when you return home, review the photographs and audio recordings, and discover that you have caught an image or a voice that is unexplainable? The feeling of satisfaction is unbelievable. Traversing ancient graveyards and historic, abandoned buildings can be a great, scientific thrill -- until you get arrested.
This is perhaps the number one rule of ghost hunting that beginners must keep in mind: don't give other ghost hunters a bad name. It is very easy to not get caught. Respect your surroundings, be conscientious of "No Trespassing" signs, and pay attention to what time the place closes. It is important that ghost hunters as a collective put out the message to law enforcement that we are just there to observe (the same message we try to send to any spirits who may be lurking around the places we investigate.) We don't want to graffiti the walls or destroy historic monuments or trample on the flowerbeds, we just want to look around.
Almost all parks, battlefields and cemeteries, unless they are located on private property on the homeowner's land, are open to the public, usually from dawn until dusk. If you want to go during this time frame, you do not have to ask permission to investigate these places. However, if you see the caretaker on your way into the cemetery, take the time to introduce yourselves, let him know who you are and that you're just going to have a look around. You'd be surprised how open-minded most people are these days, and nine times out of ten, the caretaker will be able to give you some background on the place. He might even be able to point out some interesting graves, or places where apparitions have been spotted. Some ghost hunters choose to call the local police station just to let them know ahead of time that someone will be in the graveyard behind the school. I personally don't find this necessary because I don‘t like to call unnecessary attention to myself, but that's totally up to you.
If you want to investigate a cemetery at night, on the other hand, you have two options:
1.) Ask for permission ahead of time. Call the main office for the cemetery or go there during the day to speak with the caretaker, let him know your intentions, and see if they make any special exceptions for group investigations.
If not, then your only other choice is:
2.) Sneak in anyway and risk getting the cops called on you for trespassing.
Historic buildings are a whole different story. These places are preserved by the National Historic Society and carefully guarded, which is a good thing. Nearly all of them offer public tours, however, where you will be led around the premises by a tour guide. Although these tours are incredibly informative, the constant chattering of the guide makes it impossible to record EVPs, and some places forbid photography. This is one instance when it becomes beneficial to be part of a group and/or have a lot of money to devote to your ghost hunting. A lot of historic places, like Eastern State Penitentiary for example, will allow groups to enter for an overnight, lights out investigation -- for a fee, of course. If you're interested in this option, give yourself plenty of time in advance to research the location and make arrangements. Eastern State closes down during the winter because it is not equipped with working heat, so all midnight tours or explorations must be scheduled in the summer, spring or fall.
Last but not least, if the cops do arrive, make sure you have a picture I.D. on you to show who you are. And for the love of all that is holy, don't get into a spiritual debate or legal argument with the officers. If they ask you to leave, just go. Law enforcement doesn't care if ghost hunters are at the forefront of the quest for knowledge from another realm. Don't attempt to make them understand that even though the sign CLEARLY says "no trespassing", you CLEARLY aren't doing anything wrong. Because, clearly, you are. You're better off just avoiding the drama by following these guidelines, being aware of any time constraints, and being courteous of your surroundings.