I will have to go with the Kaplan approach in regards to getting the main idea of the passage/paragraph/author. It's easy getting lost in the details, and hard resurfacing back to the main idea of things. Before I followed this method I used to always get the deduction questions wrong, because of the sole reason that I would get stuck on one detail in the passage, it would scream out to me as the right answer, while I ignored the main idea and the bigger picture. Hell, I still do that, but I got better at it. Some details don't have to support the main idea and those are usually the tempting wrong answers. The temptations have 1 sentence to support them while the correct answers usually have a paragraph+ to support them.
Also, from personal experience, it's easy to side whole-heartedly with the author on the topic and carry over that attitude to the questions. That is wrong, and unless the answer is supported 100% by the written words in the passage, its wrong. Be careful not to over-assume the author's stand on the topic, most authors don't take the extreme path in writing about a topic; they don't love or hate the issue, and if they do, you will know by their extreme language.
That's all that came to mind. Got my MCAT grade today and this logic got me to where I wanted to be.