Hint first (sensitive people get it, and you spare their dignity) then be clear (most people get it) then be brutally honest (slightly dense people get it). If I have to resort to the 2x4, then I really have to decide whether enlightening this person is going to be one of those battles I choose or one of those battles I do not choose.

This approach is fairly good. It would help if you gave examples. Also, while their is a benefit to public disagreement, sending criticism as a pm can help the recipient save face. I usually do this when pointing out grammatical errors, like the fact that I used their rather than there. It might be worth mentioning this in the orientation.

Including a very abbreviated version of the Jargon file would probably be a good idea. At minimum I'd like for it to include what we mean be rationality. Preferably with a quick discussion of http://wiki.lesswrong.com/wiki/Hollywoodrationality[(http://wiki.lesswrong.com/wiki/Hollywoodrationality), and that the word is "rationality" not "rationalism" which usually referrers to a [completely different philosophy.