Maintaining Security and Avoiding Surveillance

Having set out to become free (in both the monetary and liberation context of computing) I look back with shame at my past Micro$oft and social media use. It is truly disgusting what Facebook, Google, Micro$oft, and others have done with our information, but most disgusting of all is knowing that I ignorantly 'self contributed' so much of my own data, only to realize what I was doing too late. I guess that I am powerless to withdraw any of my information at this point in time, as once something is online you no longer own it, and it never goes away, however, having studied a great deal of Richard Stallman and Steven Rambam lectures, I have been motivated to shut down all of my social media accounts and abandon Micro$oft and Mac, and I have all but stopped using a cellphone whatsoever.

That being said, I have no intention of abandoning using a computer, and when I look into the world of 'security culture' I am overwhelmed to say the least, as much of it is simply over my head. You might say that I have the will and not the way. I have somewhat achieved a free OS in Trisquel, thus avoiding the non-free and proprietary issues, though I now focus on security and surveillance, not really knowing what to do other than removing myself from the social media spotlight. I now use a host of browser addons such as AdBlock +, NoScript, Self Destructing Cookies, Ghostery, Random Agent Spoofer, and ZenMate, but honesty I am not certain as to how effective these are, or if I am using the correct combination. Can any of you suggest what I might do to "harden" my Trisquel installation?