1.) Study first. Learn all you can about ghosts, especially the evil forces that may be hunting you.
2.) Never trespass! If you are investigating a haunted building or location, get permission first and let someone know where you'll be. If you're going to be in a cemetery, let the police know.
3.) Interview all witnesses before conducting the investigation. Ghost hunting is really a type of forensic science, so you must work as a detective, leaving no stone unturned. Ask the witnesses if they have ever used an ouija board or held a seance. These things often attract evil spirits. Find out if the witnesses are alcoholics or frequent drug users, or if they've ever used any type of hallucinogens.
4.) Never go alone! If you get hurt, someone will need to get help.
5.) As a detective, develop a profile of the ghost. Look into that person's past, find out who the are, and the circumstances surrounding their death. There could be something keeping them earthbound and you may be able to help them find peace. Remember, 99% of all hauntings are harmless. The spirit may be trying to get your attention because it needs help.
6.) When investigating a haunting (especially in a cemetery), spirits that are at rest may be disturbed and upset by your presence. Talk to them. Speak to them as if speaking to a living person. Everyone on your team should introduce themselves. Explain to them that your intention is not to disturb them, but merely to gather data that the soul continues after death. Ask them if they would be kind enough to let you take their picture. You will still get some feedback, but most of the spirits will respond to this kindness just as people do and great photos can often result from it.
7.) EVP (Electronic Voice Phenomena) recordings also work well through communication with a spirit. This is when you use an audio recorder with an external mic to capture spirit voices. When implementing this method, walk through the haunted area and speak to the ghost. Ask it questions: "What's your name?', "How did you die?", etc. Give about twenty to thirty seconds in between questions for a response. Don't over-record!! It's easy to get wrapped up in it and record two hours of tape. Just keep in mind that that's two hours of tape to wade through later.
8.) Always go to the location of your planned investigation during the day to scout so you don't get lost or hurt when you return at night.