For a few quick strategy tips on CR, you might want to check out our free tutorial here: http://www.manhattangmat.com/tutorials/gmat-logic-flaws.cfm
In the long term, however, I agree with the above poster that really you do need to study and practice.
In terms of beginning strategies, you should make sure you are familiar with the basic question types which are: find the assumption, draw a conclusion, and strengthen/weaken the conclusion. Also be able to always break down a CR question into its different components: first identify the conclusion, then find the stated premises and unstated assumptions upon which the argument is based. Once you're able to break down each question like this, identifying the correct answer should be a little easier.
If CR is your weak point, though, I would suggest buying a book so you can learn these strategies in more depth. We offer one, and I know others have already suggested alternatives.
Hope that helps!
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Caitlin Clay | Manhattan GMAT Student Services Associate | New York
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