Because of a history of psychosis in my family I decided to never take drugs in my life, not even cannabis while I life in a country where it's legal. I still got a heavy psychotic episode last year. Turns out the (heavy) drinking I participated in my student life was to blame. Research has shown that alcohol abuse causes an 8-fold increased risk of psychotic disorders in men and a 3 fold increased risk of psychotic disorders in women. [0] Not telling this to undermine the danger of cannabis for psychosis, but I wish I knew alcohol is unresponsible too I you have a high risk for psychosis. Sleeping enough, excercise, healthy diet and not numbing my stress with any substance has greatly helped as well.
[0] https://en.m.wikipedia.org/wiki/Substance-induced_psychosis