That's a great question, one that involves a detailed answer. First off, I take medication, it took 15 years of fighting with the system to eventually get on meds that work. I now take mirtazapine 30mg at night and olanzapine 20mg at night. Escitalopram 20mg in the morning. The latter was a life saver as an antidepressant. It pretty much cured my depression and anxiety. Now I just have occasional anxiety attacks for which I take promethazine hydrochloride for. It's a antihistamine that makes you drowsy so helps alot. Takes about 2 hours to work.
I used to get terrible paranoia/hyper vigilance. But it's a lot less now. I keep busy. If your busy then your focused and not ruminating or worrying about shit. I have 2 music lessons a week, practice and compose, play with friends, Buddhism, work at samaritans and domestic/social life. That's how i keep busy. Like I say the busier you are the better.