I have compiled this list of the most common mistakes ghost hunters make so you can avoid being one of those who don't understand why their geocities site isn't being taken seriously. (yes, I know, this is a geocities site)
1. Deciding the outcome before you investigate. The idea of science is to collect data and the interpret the results, unfortunately it almost always goes the other way. Even professional scientists often have a conclusion first and then find all the data that *gasp!* matches what they were looking for.
2. Believing everything you see on TV or read. If you're anything like I was, you watched a lot of ghost specials on TV as a kid, where scenes are "reinacted" and everything is made to look very clean-cut and real--- except for the tilting camera angles and transparent people. But unfotunately, even shows on the History Channel are often just plain wrong about their facts. There are thousands of teenage girls out there running around lamenting "the burning times" because they saw a history channel special on witchcraft. Well, guess what guys, none of the people who were burned in the middle ages were actually witches. You can't believe everything you see on TV.
3. Pointing to every strange thing on a photograph and thinking it's a ghost or spirit. Like a skeptical friend of mine said a few years ago, even if you did photograph something wierd, why do you assume it's a ghost? It could be any number of things. There are a few good theories floating around to even explain that "full torso vaperous apparition" that you photographed. (look up energy-trace theory)
4. Using animated GIFs and MIDIs. You can't expect the scientific community to take your 'research' seriously if you publish your findings on any website, let alone one filled with animated GIFs of howling wind or MIDIs of the exorcist theme.
5. Speaking of seriously, the next one is taking yourself too seriously. It's okay to admit that you were wrong about that orb, and admit that it is really a far-off light. Ghost hunters are often extremely sensitive about their hobby, as most people are. If you pointed out the mistakes a hard-core fisherman was making, he would probably be sore with you. Assuming that you know more than everyone else about your field, even if it is true many times, just makes you look arrogant and makes it much funnier for everyone else when your humiliated when that funnel vortex turns out to be the camera strap. So lighten up!
6. Talking down to 'nonbelievers'. This goes in hand with the above. No one likes someone who thinks they're better than someone else, and that person always falls hard when it turns out they were wrong the whole time. A lot of insecure people pick obscure fields and learn everything about it so they can have something over the people around them. That's might be fine for 3rd grade, but it gets old fast.