For RC, do 2 passages every day. While reading pay attention to the main idea of each paragraph and how the paragraphs connect together. Don't get bogged down by details.
At first, take your time on each question until you're 100% sure that you have the correct answer (find a spot in the passage that gives the answer). Then, after you're comfortable with going through passages and answering questions, start timing yourself on the passages and work on speed.
If you do 2 a day eventually it will click and you'll get the hang of RC. You have to space out the passages though. Doing a lot of passages in one day will just eat away material and tire you out. When you're really confident do more passages per day and get Kaplan 800. Kaplan 800 passages are really dense and are useful for a good RC workout.