Wow, that's really great improvement on the verbal side - congratulations!
Our tests have about a 50 point standard deviation, compared to about a 30 point standard deviation on the official test. Most of our students score within 50 points of their final MGMAT test score before they take the official test (though obviously not everyone does). We also have a bias of less than 10 points (that is, people are just as likely to score higher or lower on the official test compared to their final MGMAT test score - the scores don't consistently skew only higher or lower.
What materials are you using to study so far? In general, you do need some books that will teach you the material you need to know - not just OG books or other books with questions. I like our SC and RC books (I like all of our books!), but I'm biased of course. :)
If you already have an SC book and you're just asking how to review the material (I can't quite tell from the way you worded the question), then I really think flash cards are a great method. You can look on this page for links to flash cards that we've made to get an idea of how to make the flash cards:
http://www.manhattangmat.com/freegmatlearningforum.cfmJust one thing: try to make the flash cards yourself instead of using pre-made ones. A large part of the value is in making the cards in the first place.
For RC, I agree the passages are mostly boring, so it's really important to trick yourself into being interested. I try to think of someone I know who is interested in that topic, and then I pretend that I'm going to talk to this person later on after the test and I want to tell them about this passage. That helps. :)