Regarding SC's

The only way is practice and timed practice. You wouldn't have t time to over analyze,the other thing is GMAT SC's focus more on meaning and logic these days. This was revealed in the latest GMAC conference so work accordingly.

I sorta had the same problem (and do) but practice works and keep note what things do you over analyze and get wrong, so that you don't repeat that. Their is no quick fix to this.

All the best with your prep!

You need to develop a consistent approach that applies the SC rules - just knowing all the rules can drive you crazy. Do you know which rules are easier to spot in the original sentence and which are easier to spot in the answers? I have a consistent way of doing every S.C. in the original sentence I look for Misplaced Modifier and Parallelism - if I find it I do the work required to fix that error and then I look to the answers - comparing two at a time looking for a difference associated with a specific rule (for instance nouns changing from plural to singular would indicate that there is a subject verb error in the sentence). do the work to fix that error and keep looking until you have only one answer left.

Also remember that you are taking a standardized test with answers, you are not being asked to edit sentences. Looking at the answers to find out what the test is testing is a good way to get yourself on track for SC improvement.

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