
imaginethat
My bouts of paranoia tend to be about feeling people can read my mind or being followed/spied on, so a little different, but my strategy is to try to reality check.
For instance, re: mind reading. If it were a real thing, surely it would be known. It would be a major deal, a breakthrough of some kind. Even IF such a thing could be kept secret, it's not as if it would be a widespread phenomenon (which would also make it being a secret even more wildly unlikely). Taken further, how likely would it be such a person were on the train with me? Not very! Even if all those wildly unlikely scenarios were somehow true, they'd have a cacaphony of input (they played with this scenario in the show Fringe, and the guy couldn't STAND to be near people -- the racket was overwhelming -- and yeah, it would be(!)) Let's even put THAT aside. While my thoughts may sometimes be interesting, there certainly not as interesting as all THAT(!)
Basically, it's taking the paranoid thought and taking it step by step into the absurd showing the ever increasing level of unlikelihood that it reflects reality.
It doesn't necessarily get rid of the thoughts, but it can help tone them down.
Another thing that might help is to remember that people pay WAY less attention than we think they do. They tend to be wrapped up in and worrying about their own stuff.