One thing you can do to become a tiny(!) bit more informed is take some psych classes yourself. PSYC1030 is a popular (free) one and gives you the first glimpses into social, clinical and developmental psychology. It doesn’t give you any particular qualification but it does at least demystify some of the processes. That makes it easier to recognise the hucksters

If you’re focused in particular on getting a diagnosis for something, I’d also recommend reading relevant parts of “Psychopathology and Mental Distress” which is a tomb of a book that aggregates both DSM and ICD diagnostic criteria, but also provides current meta surveys on relevant research, from multiple perspectives. It’s reasonably easy to read but definitely better after getting the basic thinking tools from a proper course on clinical psych.