For what it's worth, here are the best practices for using these substances:

http://entheoguide.net/wiki/Main_Page

http://www.psychedelicpsychotherapy.com/content.php?122-jour...

In addition, here are some guides for dealing with difficult experiences:

http://www.erowid.org/psychoactives/faqs/psychedelic_crisis_...

http://vimeo.com/10883376

http://www.maps.org/videos/source4/video9.html

http://vimeo.com/16702478

And of course all the information on Erowid for each substance is key. Psilocybin isn't especially dangerous, but as you said if you do it wrong you can definitely end up with anxiety/depression that lasts a year or two.