Keep it simple
Have no set leadership
Have minimal organisation
Keep it small
Be open to all
Be willing to experiment with form
They also have a regularly published magazine containing many items of interest and reviews of new book publications.
You can find out more about how these work at their website: www.thejulianmeetings.net/
The Julian Meetings have a Facebook page 'The Julian Meetings' and are also on Twitter '@julianmeetings.