There are 2 important things to do:
1) get as sharp as you can at processing written english.
2) get used to AAMC verbal questions.
For objective 1), verbal skill, The standard advice is to read Wall Street Journal (If I'm not mistaken, one or more of the prep courses comes with a subscription for this reason). I can't say I've tested this newspaper myself as a tool for MCAT prep, though. Still think it's a good idea.
I personally think I benefitted a lot from reading scientific/scholarly journals. I had to read that stuff for an ongoing project, and I think it helped me get used to pulling main points and important information out of writing that sounds intimidating.
For many pre-med students like me who majored in sciences, verbal passages about humanities or social sciences can be especially challenging. You might want to find some of this material (maybe on JSTOR?) and read it on a regular basis.
It's amazing what you can accomplish with small amounts of time on a regular basis.
Also, be sure to do a lot of reading on a screen. Your speed may not be as good on screen as it is on paper, so make sure you get used to it.
Objective 2), getting used to AAMC verbal questions
I recommend the CBT's on
www.e-mcat.com
These can be purchased at
www.aamc.org/mcat
I think they are far better than any questions written by Princeton or Kaplan, because they have actually been administered on real MCAT exams.
The AAMC questions tend to fall into 2 categories:
1) questions you answer by process of elimination, drawing from your overall understanding of the passage. These usually don't require you to look back to the passage for specifics.
2) questions you answer by going to the passage for specific details. The majority are like this. You are more likely to find your answer and pick it. Less use for process of elimination.
Keep in mind that these categories mark 2 ends of a continuum, and a lot of questions are somewhere in between the two. When you practice, try to decide which kind of question it is and use the appropriate method.