SWIM (the stepdad of a friend of mine) dropped out on those regularly. He offered me/us to join, for a 6-8 hour deep experience of timelessness.
He also said, that they have to be dried thoroughly to transform the poisonous ingredients into their psychoactive metabolites, besides that there are a couple of active substances in them already. He said something about the red skin, which i unfortunately can't remember. Either it has to be left out or eaten separately, but the shrooms have to dry on a net (from above and below) as a whole.

I can't imagine that there is no youtube video on the correct preparation for safe digestion. As safe as a full fledged LSD-ish turn can be.
So don't forget the set and settings stuff before.

If in doubt, smaller doses might be safe enough as a start. The dude i referred to above was a grown out original hippie in his 50s back then (late 90s) and took these bastards as a whole, which he didn't reccommend to starters.

Stay safe.