I joined a group shortly after doing my PPL, mainly to hours build. Worked out very well. Unfortunately later on the members became complacent. It was obvious that some work needed to be done in order for the aircraft to avoid a major job the following year, but the members refused to do anything. I left, knowing that there would be a big bill to come, and this did happen.
However, I instigated the purchase of another aircraft and formed a group around that. I would say that you need a mixture of people in the group, it helps to allocate people with certain responsibilities (secretary, maintenance, paperwork, etc.).
I'd also say its much easier than you think and can be alot of fun, particularly with a PFA aircraft.
If anyone wants to e-mail me for more info, feel free.
We have a "rule book" and info pack that all new members get and I can explain a bit more about how we charge things, etc.