Read books - that's really the only consistent way that I know of and which I always recommend to others, especially to young people. Aim to read one book a week - that'd be 500 books in 10 years. Stay away from absorbing information through internet/screen - they tend to be shallow even when they are correct. Eventually you'll read a book that you agree with a lot and come out with an opinion on a topic. Later down…
For almost every topic there are nuances/exceptions/gotchas/angles and they apply as much to the person communicating to you on the topic as much as the topic itself.
Details. So many details. Seek them out because the nuances always exist and they shape how you take what people say.