Start with near zero amounts and ramp, taking notes and vitals (bpm, blood pressure). Understand yourself, the drug and have a friend nearby.
I have a low tolerance for THC, many folks consume way more than I ever could. But at the same time I have managed enjoy 200-400 mg doses (RSO). If I had taken this much at the beginning, I can see how I would have felt like I was losing my mind. I no longer have any form of paranoia, because I know what to expect. Everything in life comes down to practice and familiarity. Approach everything with a gradual slope and know what you are doing.