I actually disagree with the above poster. RC is one of the EASIEST to improve on if you really pay attention to what's being said in the passage. It's more about effective reading than blind reading. You don't have to read the passage four times. You need to understand the flow of events in concise manner. If you have the
MGMAT RC, then do their Question Banks. Their RC passages are so much more convoluted, but eventually, if you learn to pick out the main idea, theme, author's opinion and structure of the passage you're good to go.
Good luck!