I've read the book twice once at age of 17-ish and once at 22. I got very different things from it each time. I don't think that I learned some specific knowledge or skill from the book. Rather it provoked me to look differently on many things that surround me. What I found works best for me is to read few pages, select the most important thesis he is making (because he states a lot of things all over) and to write a short essay on the topic. However, at some point I got lazier, and the book became more narrative, so I switched to reading the book.