This is a very useful post. Whilst I can't condone the use of illegal substances for legal reasons if people are going to use them safely they must educate themselves and follow the kind of points you suggest.
The only other thing I would add is that it would be best to have a sober "sitter" to stay with you and watch you whilst you are taking a psychedelic. This would be similar to the role of the shaman or medicine man in ancient times.
Hopefully with the return of medical research into such agents it will only be a matter of time before they are provided for use as treatments under medical supervision and people will not have to turn to the black market.
Thank you! I share your hope that medical research will improve access to pharmaceutical-grade psychedelic medicines while also increasing support systems of psychologists for those looking to work through trauma in a clinical setting. As you pointed out, the black market is hardly an ideal place to source drugs, but yep, that's what's available now and I thought I may as well do a harm reduction post for people looking to trip but not knowing where to start.
I made a brief mention of seeking out a trip sitter, and you're right that some people would definitely benefit from a comforting presence and light supervision for backup.
Great points, thanks for sharing!