I completely agree that the right book comes into your life at the right time, whether it's recommended by a friend or staring at you in the library or bookstore!
I also found The Four Agreements to be a powerful book. The advice to not take things personally was quite life-changing as it altered my perspective. Once I realized that negative comments were more about the other person than about me, I was able to relax more and not react or be defensive, or in more difficult circumstances, just walk away without taking the negativity with me.
I think assumptions are linked with taking things personally and it's also something I'm working on. You've inspired me to re-read the book!