how to prepare for va/rc?

Reading Comprehension is important facet of CAT and requires more and more practice, the best approach in modern day is bottom Up approach where you read the questions first and then read the passage to understand the tone of the passage. The best tip is to read newspaper daily and understanding the language and vocab quickly, you should also watch TV news channels to have better soft skills and listening skills. You can also read Word power made easy, Read Bloomberg and Forbes news, and solve books by Arun sharma. Read more diverse paasages and have an unbiased views whether its contrary to passage, you should answer accordingly to the passage requirements. https://www.google.co.in/amp/s/bschool.careers360.com/articles/cat-must-read-books-for-preparation%3famp

The important aspect is reading here. Read and Practice as much as you can.
Give sectional mocks to get master in it.
Sources to read:
1. Economist
2. TheGuardian
3. Al daily
4. The Hindu
5. Project Syndicate
Important sections in this are Para Jumbles and Para Completion.
You will get RC passages of various difficulty levels.
Avoid using short forms. Learn 2 news words daily and try to use it in a sentence daily.

Also refer to some online videos to get aware of the complex questions and techniques to handle it.
Go through last previous year papers and try to understand and analyse the pattern.

Good Luck!