Facebook
First of all, it has to be assumed that you haven't put anything online that you aren't prepared to live with. If that is the case, then the advice when I was last involved was that you should know what was online about you.
One thing you can do is to be realistic about the threat - the type of threat you are talking about ie extraction of mil info under duress. Is that a current threat given your working conditions and the theatre of ops you are in?
Thereafter, assuming the worst has happened, what this type of threat involves is trying to find a weakness in you, to exploit, open up and get you talking.
If you know that your interogator has found out about your fishing habits, your passion for knitting tea cosies and your delight for 'going out of your way to tread on crunchy leaves' (a genuine facebook group) because they are all on your facebook profile - then potentially you win that round. He is trying to convince you that he knows everything about you, in fact you know all he has is your facebook profile. Solution - regular Google checks on yourself, etc to find out what is in the public domain about you. Then you know what info to worry about and what not to.