Best approach that I've found is to just know everything, all the time, always. Do that and you're golden. More seriously though, I have heard that FA and UW basically covers everything you need to know. Some of the posts from recent test takers have said the drugs they didn't recognize were just distractor answer choices anyways (i.e. not the correct choice).
thats a bad question, know ALL the drugs lol...emphasis of a given subject varies year by year so why hedge your bets, a better question would be what UPDATED pharm should i need to know than what specific drugs i need to know and in that case look at the FA errata or updates