dosage
Psilocybin content varies widely from species to species and from mushroom to mushroom. As a rough guide, however, a reasonable dose is equivalent to two grams dried or 20 grams fresh.

First time, aim low. You can always increase the amount another time, but you can't undo a far-too-large dose. Be wary of over-confidence. Each psychedelic trip is different and each level of the experience has its own intensity and pitfalls. Even if you know the lay of the land, tread carefully.