A good first time psychedelic is 2-CB [0] (low dose 10-15mg). It will give you fairly intense visuals, somewhat similar to those on LSD, with virtually no anxious or weird thoughts. As always set and setting are still important, and you should be prepared for the chance of a bad trip, but I would say you're significantly less likely to have a scary experience on 2-CB than LSD.
Note that you need a very accurate scale (measures down to the milligram) to accurately measure dosage for this substance. Please make sure you don't take too much. It is impossible to measure by eye.
it's also ridiculously rare and hard to find (requires well connected sources or pretty complicated darknet/btc/dropsite setup).
in addition to that, you're talking about a white powder drug where the effective dose is in the milligrams range. confirming purity and appropriateness of dose is stuff that requires a lot of experience. this is not beginner stuff.
[0]: https://en.m.wikipedia.org/wiki/2C-B