If you look at the way post-2013 whistleblowers have been caught, it is clear the absolute most important thing you can do to maintain your anonymity is reduce the number of places in your operational activity where you can make mistakes. Tor and Tails still do precisely that.

One of the most robust ways of using the Tor network is through a dedicated operating system that enforces strong privacy- and security-protective defaults. That operating system is Tails.