Regarding how you can improve CR, I can tell you what worked for me.
For most of the questions, the most important thing is knowing what the conclusion is. Then, depending on what type of question I have, I would approach it a certain way.
1) Strengthen type questions: Look for the answer choice that strengthens the conclusion and somehow relates to the premises. A lot of times, I'll come across choices that strengthen the conclusion, but aren't mentioned anywhere in the paragraph. This means that I'm bringing in my own assumptions and automatically I know that the answer choice is incorrect. If, going through the answers, I narrow it down to two, I look at the answer choices and ask myself if the opposite statements would overturn/weaken the conclusion. If the choice overturns/weakens the conclusion, it's the right answer.
2) Weaken type questions: Pretty much the same strategy as the Strengthen-type questions except that you're looking for the choice that weakens the conclusion or strengthens the opposite conclusion. With these types of questions, I like to quickly jot down the opposite conclusion and look at the choices that strengthen this. I see it better this way, but that's just my preference. Using the Opposite/Negation technique if you've narrowed it down to two and can't decide, the opposite answer choice statement should support the conclusion. Because it's a bit more tricky using the opposite/negation technique for weaken type questions, I mostly use it when I have narrowed it down to two.
3) Assumption questions: Once again, the answer choices should support the conclusion based on the premises. With Weaken-type questions, I don't like to use the Negation technique unless I've narrowed it down, but I feel it's something that you have to do for assumption questions, because if the assumption isn't there, then the conclusion doesn't hold. So for these questions, I'll go through each and see whether or not the opposite choice yields a valid conclusion or weakens it. If the opposite choice yields a valid conclusion, the answer is incorrect. The opposite choice should overturn the conclusion and that should be the answer. This means that the conclusion does not hold without this assumption, so the assumption must be there for the argument to work.
4) Inference type questions: I think, for the most part, that this is the question type that focuses more on the premises than the conclusion, so I make sure that I stick as closely as possible to what is being said in the paragraph and then pick the answer choice that most closely follows from that.
5) Main point questions: For questions that ask you what the main point is, just ask yourself what the conclusion is. This means that you pick the answer choice that concisely and appropriately summarizes the paragraph as a whole.
6) Paradox questions: I quickly jot down what the paradox is and look for the closest answer choice that explains it. This sounds really general, but the strategy is that simple. In the OG 12
guide, there is a question about how it was reported that apples contain a cancer-causing agent. People said that they would not change their buying habits, but the sale of apples still dropped. In this case, the paradox is same buying habits, but lower apple sales. You have to look for the choice that explains both. The answer was something about stores deciding not to carry apples. This explains the fact that people want to buy apples, but can't because stores decided to stop carrying them. Check out the question in the OG guide and you'll see.
7) Bold-faced questions: These are the questions that have two bold-faced sentences and you have to find out how they relate to the author's view, or conclusion, etc. From what I've read, a good strategy is to locate the conclusion and make a mental note of how each bold-faced statement relates to it, because the answer choices almost always mention the conclusion. Anyway, then you look at the first bold-faced sentence and the first part of the answer choice sentence and see if it's true or not. Then you do the same for the second bold-faced statement. This should help you narrow it down and find the answer.
8) Parallel reasoning questions: I don't really have a good strategy for this one. These are the type of questions that give a situation and ask you to pick the choice that most closely parallels it. I've seen people map out the situation with X & Ys. The situation will follow a pattern, for ex. if X then Y. Then you have to look at the choices and simplify to get this general pattern. I've seen atish do it on a few posts, so he would be a good resource.
One more thing to look out for is extreme words. I've read that extreme words (never, must, always, etc.) usually indicate an incorrect answer because if someone can find even a single loophole, then the answer can be incorrect. To avoid this, the GMAT prefers moderate words for their answer choices (some, most, almost, etc.). It gives them some wiggle room for their answers.
Critical Reasoning was one of the toughest sections for me, because I used to look at the answer choices and think that they all looked reasonable. I didn't know how to tackle them. I saw someone's post about Platinum GMAT which is a free site for GMAT-type questions and a tutorial (http://www.platinumgmat.com/
) and checked it out. I went through each CR question and systematically approached them depending on what type of question it was and that really helped. These questions are a bit easier, but they helped me put my strategies into practice and I could see exactly what my way of thinking should be, what I should be looking out for, why the wrong choices were wrong, etc. I would strongly recommend going through them and focusing on your strategy of how to tackle them and analyze what is working for you and what isn't and how you're approaching each problem. After this, I started going through the OG 12
guide and reviewed the CR section and it was so much clearer. Personally, I went through the Manhattan CR
guide and it's strategies are similar with a few exceptions. I think if you really take the time to practice doing questions a certain way, depending on what type of question it is, you don't need a special CR guide. After all that, just go through the CR questions on this site and you'll be fine.
I hope this helps.
Now I have to focus on Sentence Correction.