i just took mine this past saturday.
as far as RC topics are concerned.. you won't be able to really prepare yourself for it. i mean the test makers will throw 11~13 paragraphs (per passage) of random scientific literature at you and they want to test your ability to absorb and understand this 'new' materials on the spot.
your best bet is to practice and hone your reading skills by just doing lots of reading in diverse areas of literature.
i hope that helps