Although there are no proper rules for the ghost hunters, there are some guidelines which can be usefull. THere do exist books about this subject eg. Troy Taylor's Ghost Hunter's Handbook, the essential guide for investigating ghosts and the paranormal!.

ALWAYS RESPECT OTHERS PROPERTY, NEVER TRESPASS: This rule is quit important, trespassing is a crime and can bring forth a lot of troubles. And I'm not just talking about houses, churches and public places after closing time, I'm also talking about cemeteries and graveyards especially when they were vandalized. Always ask permission before entering.

NEVER GO ALONE: When you're with two or more persons, you see more than when you're alone, you always does have a witness. Although the fact that is always saver to not go alone, you don't have to be scared of being murdered, getting lost or abducted.

ALWAYS TELL SOMEONE WHERE YOU ARE GOING: It's smart to tell someone where you are going in case you get an accident.

KEEP YOUR SENSES CLEAR: Keeping your senses clear = keeping your perceptions clear. Take for long investigations some food and drink with you. Avoid alcohol, smoking or strong smelling food. These may clouding your mind and sense.

RESEARCH: I can't stress it enough, research is the key to success. Before you investigate a site, try to collect as much info as you can get. Libraries, talking to people, maps, ... try to find the cause of the haunting.

SKEPTICISM: Don't go to an investigation when you already be determined about the outcome. Always go with an open mind, the place might be not haunted. Try to eliminate all possible natural causes before even thinking about a haunting.

FALSE READINGS: It is very important to learn how to work with your equipment in a correct way, try to eliminate all possible natural causes before even thinking about a haunting. This is very important for the EMF readings.

LEARN TO KNOW YOUR CAMERA: Proper use of your camera is very important to rule out false pictures. Lens flares of incoming light in the lens can cause spectres, little water drops can cause spooky globes, fog and haze can cause ghostly forms, fingers/camera straps/wrist straps/... can cause strange objects on the picture, firing a camera flash into a mirror or highly reflective object can cause flares or spectres, etc.

WITNESSES: If you go to a location where there are people involved in the situation, like a suspected haunted house, be sure that the witness is at the location. Be sure that your witness is comfortable with the situation and understands what you are doing during your investigation. This is very usefull, because there might be natural causes involved instead of a real haunting, and you have to be careful how you explain this to the witness. The last thing you want is to be labeled a liar. Try always to explain your witness why the cause is called natural and try to demonstrate it.

FOLLOW UPS: It is always necessary to follow up an investigation. The day or night you visited the site, and you decided that there was a natural cause at the source of the disturbances, might just be a time the ghost was not active. So further investigation might be advisable. It is also important that you keep a log or write a report about each investigation, even if it has a natural cause. The report should give a detailed account and have input about everything that you did.