Just before Knutepunkt this year, US larper Maury Brown gave a talk on "harassment, missing stairs, and community safety". While video of the talk isn't up (slides are here), its now turned into an article on NordicLarp:
Its great advice for players and GMs, but note that it assumes that "larp organisers" are acting in a purely private capacity and subject to US law. As a matter of law, incorporated societies in NZ have strong duties of natural justice, and the advice it gives in e.g. #12 while perfectly fine for a GM or project organiser would be unlawful if followed by NZLARPS.