Comment by AgentMatt

> being terrified of letting loose (even with something common in the local culture, for example alcohol)

In that case, I would suggest working a bit on that first. Meditation can help, but "terrified" sounds strong enough that trying out therapy if available may be worthwhile.

Regarding substances, I found mushrooms to be easier than LSD, with a kind of warmth that softens the psychedelic experience (without taking anything away from it). The effects also don't last as long. A non-psychedelic which can allow one to face difficult emotions is MDMA. In some countries you can find MDMA based therapy. This could prepare someone to become more open to what psychedelics have to offer. (Edit: Also, all of these substances have effects that are not comparable to alcohol at all. Trying to understand the effects of psychedelics/empathogens based on experiences with alcohol is a category error.)

Based on my limited experience, I would roughly categorize the relation of these substances to the idea of control like this:

LSD: you might feel like there's some control, but you're actually the playball of the substance

Mushrooms: the substance draws you in some direction, and it's best to just lean into it, but it'll support you in doing so

MDMA: there's no need for control, things are okay the way they are

> having zero belief in the mysticism

That depends on what exactly this means.

Have some knowledge of "mysticism" or some eastern worldviews / philosophy, without taking it too seriously, would be a good basis IMO.

Actively rejecting any ideas related to mysticism while clinging tightly to a specific world view / metaphysics (and related beliefs like "I can only allow something if I understand / can explain it") may lead someone to have a really bad time on psychedelics.

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Note that this isn't advice about whether to consume anything or what to consume, and experiences can vary widely between individuals, settings, dosages etc. (For both assumptions above, is possible to construct higly positive outcomes, where the substance helped overcome problems, opens one up, etc. and negative ones, horror trip, lasting trauma from the trip, ...) Having someone experienced present when doing something like this for the first time is highly recommended.