Great question.
The New Zealanders do this very well but syndicates in Australia seem to be unusually problematic.
I too would like the secret. From my observations, everything needs to be in place from the outset. Everything needs to be in writing such that if one difficult member causes issues, the syndicate agreement is very specific and if breached that member must pay/leave or both. One suggestion is to spend half the pooled funds on the aircraft and keep the remaining half in a pool for the inevitable unforeseen engine and maintenance issues.
Syndicates have to be the way to go in order to minimise the effect of increasing charges and to make ownership available to pilots who otherwise may not be able to afford and aircraft.
Expert guidance most welcome.