Read every piece of literature on medical ethics since 1975. Seriously, there is no way to prepare for them all as some of them are totally off the wall. I read BRS behavioral science which helped a little, but not much. The bulk of them are common sense, but there's always a handful of ones that throw you for a loop.
Qbank's ethics questions are way off base too so you can't rely on those. I had questions covering everything from easy stuff like "should you yell at a patient who doesn't do what you say?" to stuff about capitation fees and the administrative structure of HMOs.
