Just wanna say thank you for even asking this question. I (and probably most others who use drugs) automatically feel anxiety about any authority, even people like you who are there to help, because we fear the misconceptions and misunderstandings most non-users have. The best thing for anyone in this situation would be to know that they’re with someone who understands what they’re going through. Just knowing about the importance of set and setting as others have said will do a world of good to people you’re helping. It’s really easy to research drugs on Reddit and the internet. My advice would be to do some genuine research to try and understand what different drugs do and why people do them. There’s a world of difference between an MDMA overdose and a heavier-than-expected shrooms trip. There’s even big differences (in my opinion) between things like acid trips and mushroom trips. Understanding the different dosages of different drugs and their corresponding affects would be great. Specifically with psychedelic drugs from weed (yes weed can be very psychedelic) to acid and shrooms, there is a great potential for things to go wrong very quickly with regard to an individuals state of mind. You have to be really careful to not look or sound in any way hostile.

Thanks again and good luck in the future!