I am not sure how helpful it will be. There aren't really any "tricks" to it or extensive strategies for RC. And I took the Powerscore class and like it was mentioned, they basically just cover the topics of passages - sciences, markets, historical etc.
Key is to not read too fast, or too slow. I get done reading and marking the passage in about 2 minutes. Be an active reader, continue to ask yourself as you are reading "what point is the author trying to make".
Mark down where there are obvious changes in scope/opinion/tone of the author.
Mark dates & names and strange terminology.
Be aware of the structure of the passage: How is it put together? P1: Intro/Thesis Statement P2/P3: Pros/Cons, Elaboration on examples etc. P4/P5: Authors opinion/Concluding remark
That plus reading lots and lots and lots. I read everyday - mostly heavy condensed scientific papers, I would recommend reading material that is laborious to read and understand.
This strategy I have been using, I usually get 0-1 wrong on the RC section.