Some of the things you need to watch out for when trying to capture anything supernatural on film.
If you have long hair, keep it put up or pulled back
Take your camera strap off or make sure it's looped around your hand
Try not to aim towards direct sun or bright lights
Keep an eye out for bugs
Test to see if you can see your breath in the air
Make sure you or the people around you are not smoking
The dust factor is still open to debate, but make a mental note if you can see some in the air
Don't take pictures in the rain or snow
Check for reflective objects. Such as mirrors or glass