Much of each person's experience with psychedelic substances is based on SET and SETTING. Set refers to a person's mental and emotional makeup, expectations about the experience, cultural upbringing, etc. Setting is the immediate environment and stimulus present during the experience, whether outdoors or in a building, with friends or alone, the presence or absence of music, artwork, etc.
If I had to choose one setting as being the most conducive to a positive experience, I'd pick one which most closely resembles the time honored methods of using these substances. This would involve taking a natural psychedelic like mushrooms or Peyote. It would be done outdoors in nature, away from the noise and activity of any city and with a group of respected friends or family. For novices being initiated into the psychedelic world, the session would be guided by trusted and experienced "elders".
- from The Essential Psychedelic Guide by D. M. Turner