I think one of the most important things to know is that subject I touched upon in the other thread; Self-Certainty.
Not all "OTs" have it, of course, some doubt themselves but when dealing with most of these guys you should understand that they are of the firm belief that they already know ALL the answers. Hubbard went to considerable length in discussing the subject of self-certainty, he spoke of it as
the most valuable thing a Being could possess.
Much of the behavior which seems inexplicable (or hard to grasp) stems from this simple fact; regardless of the rightness or wrongness of a thing, the OT has adopted a viewpoint of certainty about it as regards himself.
Self-certainty! He has it and, if you're not also OT like him, you don't.
It's just one of the more important reasons why it's so hard to overcome an OT's unwavering resistance to new (non-Hubbardian) ideas.
I don't think I need to expound on this too much, when it comes to dealings with OTs, it's quite an obvious thing.
I'm completely certain of the above!