Speaking of "Don't be a dick!" (which we actually weren't, but a lot of other people have been talking about this in the last few months), here's a lucid post on the subject by Alan Baxter. Please note that he is not writing in the context of any previous advice by or to anyone about being or not being a dick, or in the context of any resulting controversy.
His examples are pretty good ones. They amount to not being petty, shortsighted, unprofessional, and thoughtless.