How do you engage and approach a patient presenting with psychotic symptoms who has demonstrated a pattern of malingering and also has polysubstance use disorder?

This is a nice general summary of some basics, non-judgemental, supportive approach, quiet/low stimulation environment: Mental Health First Aid Guidelines.

With regards to malingering and how to approach it, try to determine the real want/need (housing or food insecurity?) and if it is something that you and your team can help work on with the patient. With regards to psychosis, I do a thorough review of systems, physical exams, and work up any findings, and rule out medical causes of psychosis. If there is any recent history of the patient having been assaulted or having any head trauma, consider a head CT if possible. Try to speak with people who know the patient (e.g., family, friends, prior treatment providers) to get a good understandi...