Basic Equipment
Every good investigator needs to write and log in everything that happens. If you don't then you really don't have much research information.
A note pad and pen are essential for recording the time and description of paranormal events which occur during investigations. It's a lot easier to find the information you need in a note pad rather than fast forwarding and rewinding through an audio recording!
____________________________________________________________________________________
A digital voice recorder is required as a personal item and should be on every paranormal investigator's must have. I prefer the Olympus VN - 3100PC pocket-sized recorder with nearly 72 hours of continuous recording capability.
The easy-to-use thumb pad makes for quick and convenient operation of functions like file management, choosing playback and recording modes and more. Timer recording and voice activation provide awesome versatility.
____________________________________________________________________________________
The one item I suggest to all new ghost hunters is the The Ghost Meter. The Ghost Meter provides three corroborating indicators of EMF emission strength. A needle based display, LED lights, and an adjustable audio signal.
The response time of this meter is excellent, easily outperforming more expensive EMF meters. It can also be operated in silent mode so it doesn't interfere with EVP (Electronic Voice Phenomenon) recordings or distract other investigators during an investigation. Compare the value this meter offers compared to other brands.
____________________________________________________________________________________
Digital or film cameras are perhaps the most invaluable tool to have, and every investigator should have them. Solid, visual evidence of the spirit world is often the most compelling evidence that can be obtained.
I prefer digital cameras because they can hold dozens (or hundreds depending on the storage capacity) of pictures, and I can view the pictures instantly, and I don't need to buy film and pay for film development.
____________________________________________________________________________________
Digital infrared thermometers are helpful in finding temperature changes from one location to another, often only feet from each other. When ghosts draw energy, they often leave pockets of "cold spots" in the air, which is another way to help detect the presence of spiritual activity.
One drawback with this type of thermometer, however, is that it measures the temperature of the object the laser is targeting, therefore, the result is the temperature of an object, not necessarily the "space" where potential paranormal phenomena may be. However it is useful to read temperature changes on doors and walls where one feels a presence may have recently passed.
____________________________________________________________________________________

Video cameras are especially useful in documenting an investigation, and is often the most expensive tool in an investigator's arsenal. It is best to invest in a good recorder, one that will last a long time and meet your needs.
It is wise to use one that has a "night shot" feature for filming in low light. If it is not a night shot then you can use the Sema IR light to capture clear digital footage in low- or no-light situations.
____________________________________________________________________________________