I'm by no means an expert. This is a hobby... or perhaps quest is a better word. At any rate I can give you pointers that have seemed to help me yield good results over the years.

• Camera Type: I prefer 35mm with flash built in though I have picked up orbs using disposable cameras as well as instant cameras. What you need to realize is with different types of cameras you are going to be looking at the same orbs with a slightly changed appearance. I'm not a camera expert either but I'm supposing it has to do with speed of the camera. I have never used digital or video. I have heard camcorders have to be modified to pick up orbs.
• Film Type: 200 speed. I'm picky about it. 400 or 800 doesn't work for me near as well. 100 has the obvious problem of no flash.
• Conditions: The best time is not at night. If you want perfect conditions take your pictures during heavy overcast or at twilight. If that's a problem then night is your next option. I have caught orbs during very sunny conditions but it tends to be in the shade and it's not often. If you are taking pictures indoors then you will need to experiment with lighting. Be sure to keep your lamps behind you because of lens flare.
• Lens Flare: It's the light that can trick you into thinking it's an orb. It can be caused by the sun, lamps, streetlights, flashlights and headlights. As you take the pictures try to remember where artifical lights are positioned. It may even be a good idea to jot down a few notes. It can also show up as a red streak. Another thing that may cause red streaks is exposing the film...so look at the location of any abnormalities in conjunction with the beginning and ending of the roll.
• Help at Night: If it is particularly dark outside I have used headlights or flashlights. Again, remember to position them in a way that they will not cause lens flare. It is a good idea to note which pictures were taken with additional light.
• Processing: I have used several different photo developers and have done both overnight and one hour. It doesn't seem to make a difference.
• Property: I strongly advise you to seek public property or get permission from the property owner before you trespass. Stay within the law.
• Additional: I have noticed talking out loud helps. Just a quiet voice. I kind of explain what I'm doing there.