I've never studied for CARS, which I thank God for since I had to study nonstop for Chem and Physics. 90% of the time the first instinct you have on a CARS passage is right, so I answer all the questions, even if I mark them, then I go back at the end. It gives me a piece of mind haha. I have 3 things I normally follow: 1) Read the whole passage first. I know many people do questions first and then go back to the passage, but I find reading the whole thing lets me go faster. I normally finish within a hour. 2) For each paragraph write a few words on the main idea. I then go back at the end and write a huge main idea. This helps so much because so many questions deal with the main idea, or the author's view on certain topics. 3) Translate the question. Sometimes there are long and convoluted questions that no one can make sense of. I take that and shorten it into a few words and make it easier. This took practice initially, but it helps so much. Also, unless you are super certain you were wrong, don't change answers. The questions I tend to miss were ones I switched back. Trust your instinct on CARS.