by RonPurewal Fri Oct 12, 2007 4:36 am
This is an awfully general question...
The best thing you can do is PRACTICE. Do tons and tons and tons and tons of practice CR questions, and go over the answer keys RELIGIOUSLY. Try to absorb any patterns you detect in the types of inferences they're looking for.
If you're really motivated, check out 'Critical Thinking: An Introduction' by Alec Fisher from your local public library (or buy it from amazon). It's very British, but it's easily the best critical thinking textbook I've seen. And it's only about twenty-five bucks (that's 1/10 of the GMAT registration fee, if you're keeping score at home).