Benzos will only destroy the meaning of the trip, preventing it from having therapeutic psychical effects and lessons that might be integrated into your everyday life. They should only be given if an individual is having a psychotic/irrational response and could potentially be a danger to themselves or others. Anxiogenesis on the come-up, for example, is normal and rushing to benzos will cause you to miss the point of the trip. Obviously all other prescription medications are a given. Other than that, good music and something to kill the weird dry-mouth sensations that 5-HT2a agonists cause.
It is tough for me to say, however (my ideal psychedelic kit would consist of LSD, DMT and more LSD). I usually always trip alone and use fairly profound doses when I do and have never encountered a crisis or a 'bad trip.' But I know myself and my reactions to a wide myriad of serotonergic psychedelics across the dose-spectrum extremely well. If you don't and are new to psychedelia, then the best "crisis" preparation is to have a good friend with a sympathetic ear. That's usually much more helpful than alprazolam.