It seems like your best section is SC - CR and RC are average and if you don't improve on any of these sections, your score will remain in the 600. I'd suggest you get more practice with CR.
Try this practice CR question here: http://www.gmatpill.com/gmat-practice-t ... stion/1192
The hard part about CR is two steps. You have to understand the complexity of what they are talking about. I recommend visualizing in your head the information that is presented in the passage. Once you can visualize and have arrows in your head pointing to where things are going, you then want to focus on the question - which is the ARGUMENT. Are we strengthening it or weakening? What are the possible ways to do each? How do you structure the argument? You want to have an attack strategy for all of these questions.
For RC, you should check out the RC Pill
videos - there is a free demo on the site for two passages. You can check out the approach and use that strategy for all your RC passages. The key thing about these videos is knowing what to read, what not read, and how upon reading a question, know how to scan through a passage to get precisely at the answer.
... and more
What's Inside GMAT Pill?
Zeke Lee, GMAT Pill Study Method (Study Less. Score More.)
GMAT Pill Reviews | GMAT PILL Free Practice Test