The thing I like most about the paranormal genre is the lack of "normal" in anything. Whether vampires and werewolves strut across the world, or it's winged fairies, goblins, imps or ghostly residents or another sort of being creating havoc, the potential is there for alot of fun and excitement.
Is there a standard way to write one? Are there rules one must follow in order to be considered good paranormal writer? I don't have the answer, but for me I've found if you build a world (or even use your existing reality) you've got the hard part done.
When creating a paranormal, not only do you need a cast of strong characters, you need to decide beforehand what the tone is going to be: serious, dark, light-hearted, funny? Anything is acceptable as long as your plot is believable enough to carry the story. Believable in paranormal? You bet. I'm a firm believer that anything can happen in our world, and just because we can't see it or haven't yet encoutered it, doesn't mean it doesn't exist.
Bottom line? Anything goes in a paranormal story. And the biggest thing? Have fun. If you enjoy it so will everyone else. Who knows? You may just make someone else believe too!