Be predictable and confident. Whether its a cyclist or a motorist, the most annoying and therefore dangerous to me are the ones that are timid and do unpredictable things.
Nothing you do is going to protect you from the one stupid person or irate with road rage out of all the good motorists or cyclists that comes up behind you suddenly. By the time you recognize them as that person intent to do you harm, it'll be too late to avoid them.