Do you have any more resources for reading comprehension (RC)?

Yes! I'd definitely recommend checking out our blog:

http://magoosh.com/gre/gre-reading-comprehension/

If you scroll down the page, you'll find a lot of posts about how to improve on RC :)

Additionally, these posts are particularly helpful: 

• GRE Reading Comprehension - general overview
• How to Approach GRE Reading Comprehension - strategic tips