Unfortunately, reading comp is the one area where there are no "quick fixes". Make sure you've gone through the reading comp book and understand the STOP method to reading for the GMAT. Sometimes, students can improve a few points by simply changing their approach to reading.
It sounds like you aren't a native English speaker. That certainly makes the reading comp section more difficult. As I said, there are no quick fixes here. Put simply, you just need to get more comfortable with written English. The best way to do this is to read as much well-written material as possible before your exam. I recommend the Wall Street Journal. Try to work in 30-60 minutes of reading into your daily study routine. That type of "cross training" is a great way to improve without actually doing GMAT problems (which can get tedious). This will also help your other verbal areas, but it seems that you're struggling with RC in particular.
Of course, also do GMAT reading passages. At the very least, make sure you've done the ones in the Official Guides as those were written by the GMAT testmakers. Be sure to break down and analyze the questions, paying particular attention to why the wrong answers are incorrect.
Good luck! Remember: if there were a quick fix, everyone would be able to do it. Success on the GMAT depends on hard work and determination!
Jim S. - Veritas Prep GMAT Instructor (Los Angeles, CA)