Orb photos
Orbs are believed by some to be spirit energy. Personally they don't impress us.
"Dust orbs"
It is important to keep your camera lens clean. A dirty lens can make it look like there are orbs everywhere. Don't take pictures while walking down a dirt road or while moving about in a dusty room, because you will be kicking dust up into the air. Remember that just because you didn't see any dust in the pictures you took right before and right after you got an orb pic does not mean there was no dust. The dust was there, it was just out of frame.

Precipitation
Don't take pictures in any kind of precipitation. Even when it has just stopped raining, there's still moisture in the air and the water droplets can look like orbs. This is a picture of snow.

Some other things that are commonly mistaken as orbs are glares, lens flares, and light refractions. Only about 1% of orbs are not dust, moisture, or camera defects. These you can actually see with your naked eye and they give off their own light. However, these are associated with natural phenomena like ball lightning and St. Elmo's Fire.
Mist photos
If you're taking a picture and it's cold out, hold your breath so it doesn't show up in the photo. Also, don't smoke or light candles when taking pictures. Moving rapidly from a cold to warm temperature may cause condensation on the camera's external and internal surfaces, which can look like a mist. The photo below is of breath in front of a camera on a cold night.

Camera straps, body parts in view
Be mindful of your camera strap, finger, hair, or anything else getting in front of the picture. These can look like anomalies when illuminated by the camera flash. Here are some examples of what a finger can look like.


This is a camera strap...

And hair...

Camera problems
You should read through your camera's manual so you know when you're doing something wrong, and you can become familiar with all the different kinds of camera defects.
Long exposure time
If someone walks quickly by the camera with no flash and a longer exposure time, the result will be a semi-transparent image that looks like a ghost. If they're wearing black, they will look like a shadow person.

They can appear to be missing an arm or a leg, because they're moving so fast.

Also if your camera is set to a longer exposure time and you move your hand, it can create blurs and streaks. If an insect flies past, it will look like a "rod". Rods are not paranormal.
K-II Meters

A K-II Meter is a kind of EMF Meter made popular by ghost hunting shows. They're popular because they go off more than some other EMF Meters, but that's actually because you get more false positives when you use one, not because they work better. Cell phones set them off (even on Silent mode), wireless Internet sets them off (even if someone in the house next door is using wirless Internet), walkie talkies within 50 feet set them off, and car alarms set them off. The power button is a bit tricky because you have to keep holding it down with your thumb in order for the device to work properly. As you can imagine, your thumb will eventually get tired and when that happens, the light will flash, giving you a false reading. They do have their uses, but they're overly sensitive. If you're going to use a K-II Meter, we would recommend always using it alongside another EMF Meter, preferably a Trifield EMF Meter.
The Frank's Box

The Frank's Box, also known as the Ghost Box, is a device that some people believe can be used to communicate with spirits. It's basically a modified AM/FM radio that continuously scans through radio frequencies and produces white noise. The spirit is supposed to be able to manipulate the white noise to form words that you can hear with your ears while you're asking it questions. The Frank's Box is good for parties, but that's pretty much it. Since it is scanning through radio frequencies, you will hear snippets of words from DJs, newscasters, and songs. Sometimes you might get lucky and hear a word that seems to answer a question, but it's just a coincidence. In order for this to actually work, a ghost would need to be able to predict what every single person on every radio channel was about to say and be able to manipulate it to get the word it wants.
The Ovilus

The Ovilus is another device that some people think can be used to communicate with ghosts. The disclaimer says: "The Ovilus is sold as an entertainment device only. We make no claim to the validity of the data received by these devices...Further this device should not be used by anyone with a history of mental illness." Supposedly, it works by translating EMF readings into numbers, and then further translating those numbers into words using a speech synthesizer. How exactly it does that when nobody knows if ghosts even exist or what they are, let alone how the person who built it interpreted an EMF reading of X to equal a certain word........I have no idea. It has 2,048 words pre-programmed into it. However, the disclaimer also says: "Odds of this device saying a word that is contextually correct is 1 in 2,048, Hand Held. And in using phonetic speech the odds are only 1 in 71."
Audio
In theory, Electronic Voice Phenomena (EVPs) are ghost voices caught on tape. You don't hear anything when you're recording, but then when you play back your recording you do. While there are some audio clips we haven't been able to explain, we believe that real EVPs are not as common as many paranormal groups believe, and about 80% of the EVPs posted on the internet are explainable. When we record for EVPs we always have two voice
recorders running at
the same time so we can cross reference, and we have a video camera
recording us with everybody sitting so they're in frame and facing the
camera. We begin every investigation by allowing a half an hour of
controlled
silence so that we can document the regular sounds the building makes,
then when we're ready to start recording we sit together and have
everyone identify themselves into the recorder. If anyone makes a sound
or hears something that could later be mistaken as an EVP, we say "that
was a stomach" or "that was me shifting" into the recorder.
Some EVP could just be bleeds from CB radios, wishful
hearing, or noises made by living people or the environment. If you're using a cassette recorder
without an external microphone, you will record the sounds the gears make
inside your recorder. Also, never rerecord over a used tape as voices can bleed
through.