When working with a pagan group, you need to develop a sense of the pagan psyche. Since power is a constructed illusion agreed to by the people managing or distributing said illusion, this tendency to remove the assumptions can make corralling for a common purpose difficult at best. Even in large groups, there is both a tacit demand for consensus and a subconscious struggle to establish pecking order. Ultimately, it's up to the person initiating the group to decide how these inevitable aspects of human nature can be handled. Agree to a leadership model and a time frame for the model.
Some models work for a set period of time and then change.
For example, if you run an open membership group, consensus might work well at first, then abruptly become useless when the group grows suddenly. Evaluate every session. Pass a talking stick, send in a secret ballot, have a wrap session at the end. Give each individual group autonomy over their particular task or event, but request they abide by any ethical or procedural guidelines they had agreed to as part of the greater group. Be prepared to re-work everything from what you call an office to how you manage record keeping.