Deciding who to take along with you on your ghost adventures may be one of the most important decisions you make. Besides the fact that you want individuals who have the same paranormal belief system as you (What use is a psychic on your team if nobody else believes in psychics?), you will want to take along people that you trust implicitly. If a member of your team approaches you with an eyewitness account of a full-bodied apparition appearing in a certain location, there should be no doubt that what he or she is saying is true.
Because most people only have a handful of friends they trust in this capacity, many paranormal groups opt to keep their team small. My group, Paranormal Inc., is one of these teams. We only have three members—and the other two are my brother and a friend I have known for over twenty years! Another advantage to having a small group is the lower likelihood of contaminating your own audio/video footage. The fewer folk that you have tramping around a house, the fewer people you have to worry about keeping track of. Ideally, you should know where everyone is at all times by tagging your audio/video and keeping a log book during your investigation, but when you have a large number of people at an investigation, doing this is almost impossible.
Unfortunately, many paranormal groups go to extreme lengths to get as many "members" as they can. They do membership drives, constantly recruit, and often do open investigations that allow untrained individuals to wander throughout the location being investigated. What’s the point of this? Evidence gathered during such an investigation cannot be taken seriously due to the high probability of contamination. If you are looking for a social club, then make your group a social club! There’s no advantage (and numerous disadvantages) to having a massive paranormal group unless you’re more concerned with selling merchandise to your "members" than you are with seriously investigating the unknown.
When you make your decisions concerning your team, consider making it as diverse as possible, too. Try to have at least one female member and one male member. Experience has taught me that sometimes certain entities have an easier time responding to a certain gender than another, so it’s nice to be able to try different approaches.
Of course, many paranormal enthusiasts go another route as well. Since some people do not have any friends interested in the paranormal and don’t want to join an existing group, many opt for investigating by themselves. This is perfectly acceptable, within reason. If you are going to a place with on-site workers and patrons (such as a hotel, B&B, restaurant), there should be no problem with you investigating on your own. Just watch your step while moving around in the dark and keep your cell phone in your pocket (though turned off so it doesn’t interfere with your equipment).
I certainly do not advise doing an investigation at an outdoor location by yourself—there are simply too many factors beyond your control (wild animals, weather, terrain, etc.). There is also a practical reason to have at least one other investigator with you—if you see/hear a paranormal event taking place, it’s nice to have that corroborating witness!
From Ghost Hunting for Beginners, by Rich Newman.