Study "support or strengthen" questions and the opposite, "oppose or weaken" questions. These questions ask you to read a short paragraph and then ask you which of the answer choices "support or strengthen" or "oppose or weaken" the author's conclusion. Make sure that you can restate the author's conclusion in your own words in the simplest manner possible. Look at all the answer choices and then put a check if they agree or a minus if they agree with the simple statement that you drafted in your own words.
Study "assumption" questions, one of the most common types of questions on the GMAT. These questions require that you read a short paragraph and then asks you things like, "The passage assumes which of the following?" or "The conclusion is dependent on which of the following to be true?" The key to answering these questions is to cover up the answer choices with your hand and then state in your own words what you think the passage assumes. Once you have this clear in your head, uncover the answer choices and find the one that matches your answer best.
Study logic pattern questions. These types of questions ask you to read a short paragraph and then identify the type of logic used in this paragraph. For example, the question might ask "The passage uses which of the following types of argument to support its conclusion?" or "The author nullifies the police’s conclusion by:" and then you must choose the appropriate answer. You can answer these questions by finding the spot in the passage where the logic of the decision or conclusion is stated. Even if you don't understand it perfectly, you should match it to the answer which best describes it.
Study analysis questions. These questions are very popular on the GMAT and very simply ask you questions such as "According to the passage, which of the following can you infer/must be true?" For this type of question you must eliminate answers by going through each of the answer choices and saying "This answer is wrong because..." and using evidence from the passage to help you. The correct answer choice should then be obvious.
Study explanation questions. These questions ask you to read complex theories or descriptions of conflict and be able to pick the answer choice which best summarizes them. With this type of question, you really need to be able to summarize what you read in your own words very simply. Then select the answer choice which best matches the summary that you came up with.
Practice critical reasoning questions for at least an hour a day for four to eight weeks before the test. You can purchase a GMAT preparation book that will have tons of critical reasoning practice questions or you can just go to a website like Study Guide Zone or Best Sample Questions or Platinum GMAT (see Resources). The more you practice and the more familiar you are with the type of questions the critical reasoning section of the test asks, the faster and more accurately you can answer these questions.