Another thing that you can do is go onto the Live Chatter and speak to people about Covens. I know Zebrah (Zeb) frequents the chatter and is popular, you can ask them or even send messages to Coven leadership, Priests/esses, Councilors. As Councilor, and Former Priest, of Divine Essence I can share a bit of what it was and what it is now.
In terms to active groups, Spell Casters might be the most active due to it being so large along with Black Cross. However you won't know until you join . So I advise that you simply do some research and talk with people. That is your best bet friend.