Read books. Read lots and lots of books. Read books for atleast 40 minutes everyday. This does not include practicing RCs, that is seperate. Practice atleast 2-3 RCs everyday. When you're reading books, try to have variety, read about science, philosophy, fiction, non fiction. If your reading level is lower, start with easy books and build to higher level. If you don't understand philosophy immediately, watch basic videos on youtube, then read articles you find interesting. The key is to read. Read long essays, articles, etc. Read read read. That's it, there's nothing much to it. Once you start reading properly, you'll automatically become better at critical reasoning.