All ghost hunting instruments are important and effective when used appropriately. The EMF Detector is one of the main instruments used by ghost hunters from the novice to well experienced. There are many different kinds of EMF Detectors on the market today. The these can range in price from $75.00 to around $150.00. After purchasing  a EMF Detector make sure you practice using it around your house. This gives you a chance to learn how to use your new detector. Also this will give you a chance to learn the different things in a home that give off EMF, and what kind of readings they give off. Examples would be Lights, Outlets, TV's, and Power Panels. All of which you will encounter in any home you are investigating. This will help you during an investigation to determine if a reading is normal or paranormal. A reading between 2-10 mG could indicate the presence of a spirit or other paranormal activity. So know your equipment before starting an investigation. It will save you time and frustration during an investigation.

What we are looking for in a paranormal situation is a reading of 2mG or higher that can not be explained by a man made power source. You may find a reading that fluctuates for no explainable reason. It may be that you have a reading of 2mG that suddenly jumps to an 8mG, Or you may have a steady reading of 1.9 that suddenly drops. This could mean something in the room is trying to manifest its self. You may also find a high reading  that moves and you can follow around a room this is a good sign that it is paranormal activity.
If you do find a unexplained EMF Reading try to back this up with some other phenomena such as a cold spot, strange feelings of heaviness or Orbs. Every thing you can do to back up this evidence makes you findings more credible.

How to scan a area using an EMF Detector:

When scanning an area for EMF start by scanning the area with a slow swinging motion. Start with a side to side motion followed by an up and down motion. Do this slowly and smoothly as sudden movements could affect your readings. Do this and cover the entire area being investigated. Remember you are looking for spirits witch could be located any were, Near the ceiling, Floor, or right in front of you. So cover as much area as you can.
When you find a high EMF Reading try to follow it and see if it is being produced by a man made power source, or is it an independent energy source. So be very aware of your surroundings. This will save you time while trying to determine if a reading is normal or paranormal. If you are reading a 2mG or higher and you can rule out all man made power sources then you are most likely detecting some sort of paranormal activity.
and now would be a good time to try to take a picture of that area for later review. It may be that if you have  high reading you may capture something on the camera. Also check the area to see if there is a cold spot that corresponds to the high readings.
And that's all there is to it. Know your equipment and go have fun. That's what its all about, having fun. Hope this helps please let me know what you think. Comments are always welcomed on my site Good or Bad.