Earlier I reflected on Gus di Zerega's arguments against having Pagan clergy.
A friend commented that if we're going to have clergy, maybe we should look to similar religions to Paganism(s) for role models.
Good point - but what religions are similar to Paganism? The nearest (as far as I can see) are Unitarian Universalism and Quakers (the Religious Society of Friends). Also, I would argue, liberal Judaism.
Well, out of those three, Quakers don't have clergy. The other two, however, do something very significant: the congregation selects the minister / rabbi. If you look at traditions where that doesn't happen, it's a recipe for trouble. Somebody gets a nice "bells and smells" thing going, and then the evangelical wing gets wind of it and sends in a bully-boy to stop it all turning too Catholic. OK, so people can vote with their feet, but what if that was the only high church game in town? Whereas, if the congregation selects the minister, they get to choose someone with a similar theological outlook and value system. In Wicca, the founder of the coven usually gets to be High Priest/ess; but there's usually more than one coven in town, so if you don't like the values of Coven A, there's usually Coven B and C just down the road; so you can vote with your feet (or found your own coven if you have enough experience); but that relies on the various covens having different values for seekers to choose from. In Heathenry and Druidry, which tends to have larger groups, there is usually only one group in a particular place.
So, we all need to be more up-front with seekers about what our values are. I think this is why there are so many solitary practitioners; I hear so many people say that they didn't like the ethos of the groups they tried. Sure, your coven/grove/hearth is LGBT-friendly - but do you mention same-sex love in your rituals? Sure, your group is consensual - but do you have a consensually-agreed-on set of guidelines that the whole group has worked out, which you can refer to when one ego tries to dominate? Sure, you're not authoritarian - but do you make people copy out the Book of Shadows?
Gus also worried about using the word "clergy" for our spiritual leaders. I agree that this word is probably not quite the one we want, as it doesn't encompass or imply witch, priestess, shaman, etc. How about gytha and gothi for Heathens, druid for Druids (I dislike the word druidess), priest and priestess for Wiccans - oh wait, we're already using those. I suppose we need a collective term for all of these that can be readily understood by the rest of the world.
The power of the "clergy" should be balanced by having a strong and well-informed committee or other body to which they are accountable (this mostly works fine for synagogues and UU churches).
In a Pagan setting, there should not be sermons; only talks and discussions. A Pagan ritual shows the way; it doesn't tell you the way, but leaves you to work it out for yourself. Similarly, a UU minister does not give a sermon; she or he gives an address, which the congregation are free to ignore, shred or take on board as they see fit. Some churches have a discussion instead of or after the address. In our coven, we use a talking stick for discussions; this works well to ensure everyone gets space and time to be heard.
The relationship of Pagan leaders to Pagan groups should be one of service offered to the community (not imposing orthodoxy); and rather than carping and complaining, people should be ready to take on leadership roles. Of course the passing-on of the mantle can only occur if the existing leadership empowers and encourages their successors; so all our interactions and training should be about empowering others and not keeping them as mere neophytes. (I've always said that I'd rather empower people because it's less effort than not doing so, quite apart from the ethical considerations).
Another good plan is to have an annual general meeting of your hearth/grove/coven where any issues can be brought out into the open. This can be opened and closed with some simple ritual act, such as grounding and centering, and is probably best facilitated using a talking stick; but I have found this very helpful in the past.