I'd start with https://en.m.wikipedia.org/wiki/Psychology
As frameworks and quick references to concepts. I'd go over an introductory psychology textbook, if you go deeper preferably a biopsychology or neuropsychology book. You need to def know the material conditions which can only be gotten doing a bit of the life science part on the nervous system and (breach psychiatry) while doing it get some understanding of drug effects and what they aim to do and actually do) but really that might be going to deep into medical application side. Ultimately you might consider just above links and maybe some sources on therapy types and behavioral psych. It can be steep and a deep end into pharmaco or cognitive science parts imo.
You should start by starting a business it will teach you all you need to know about psychology .... and some more :) I'm doing business and psychology/self development for the last 7 years and unfortunately, the idea of being good at business because somebody is good at understanding human behavior has huge flaws.