I am suggesting a method of study that will help you dramatically improve your proficiency in CR within two weeks. This approach has worked for me and I am sure it will work for you also.
The following is a part of my de-brief in the Share Your GMAT Experience thread. I believe this method will help you. Remember, the principles will work for you if you work the principles.
1. Powerscore GMAT CR Bible -
An excellent book for improving oneself in CR! The best way to study it is (pay attention, this is important, I don't think anyone has mentioned this approach before) as follows:
The first few chapters in the book offers a brief overview of what CR is all about. The remaining chapters focus on specific question types. The book divides CR questions into 10 different types and the introductory chapters will tell you how to distinguish one question type from another. After learning the introductory chapters, do the following:
Keep the Powerscore CR
Bible next to you and turn to the CR section of the official guide. Start with the first CR question in the official guide and see if you can classify the question type. If you can't refer back to the introductory chapters. If you are able to classify it, turn to the relevant chapter. Go through the chapter and then return to the question and see if you're able to get to the right answer by applying what you just learned. If you're not able to get the right answer, go through the chapter again and again till you know why the right answer is right and why the wrong answer is wrong. Keep repeating the procedure for every question you do till you reach the point where you can start solving questions without having to refer back to the text. If everything goes as per plan, you should get there by question number 60 to 70 in the OG. From there on, do the remaining questions under timed conditions. I assure you, by the time you finish with the CR questions in the official guide, you will be able to breeze through the 500, 600 and possibly the lower 700 level questions in the actual GMAT :D