And finally, a Step-by-Step approach for Critical Reasoning:
1. Read the question carefully - don't try to save time here by skimming
2. Identify the type and the structure of the argument. In some cases, the question might be fairly straightforward and recognizable. For e.g. boldfaced questions or mimic the reasoning. But some questions can be trickily worded. For e.g. flaw in the argument, inference etc.
3. Next, identify the premise, conclusion, counter-conclusion etc.
4. Come up with a one sentence summary of the argument with the help of keywords- Premise Keywords such as because, since or due to, and Conclusion Indicators such as thus, hence and therefore
5. Try to anticipate the answer without the answer choices
6. Apply the process of elimination - try first to eliminate answer choices that are irrelevant to the argument or "So what?" type.
7. Look for common CR traps: for e.g. reverse causation, alternate causation, statistical traps and so on. Don't fall for these!
Do remember that there are no universal rules/techniques for GMAT Verbal, and you shouldn't try to look for catchall formulae or short cuts. Have a focused, systematic approach, look for thumb rules, and learn from your mistakes. Most importantly, keep at it and don't give up!