Crawdad, I obviously don't know anything about you and how you go about solving SC problems, however, I think a lot of people tend to think too much. They want to apply a rule to every answer choice in order to prove it wrong or right. Honestly, as a native speaker, most of the time, simply reading each answer choice as a part of the question prompt will allow you to eliminate 2-3 answers without even thinking about rules or idioms or parallelism - they will just sound bad. Of course when you get to some of the more complicated questions and answers, you will have to apply some "technical" knowledge. Having said that, it was surprising to me how far you could get, even on the really tough questions, with the basics.
Parallelism is huge (and luckily, not terribly complicated most of the time). "Which" after a comma must describe the word immediately before the comma. "When" must refer to a time, "who" must refer to a person, "where" must refer to a place. Don't get these mixed up.
Using some of the simple rules like these along with your native ear, can, in my opinion, get you to a high Verbal score. Don't waste time trying to apply obscure rules to answer choices that sound awful.