A few thoughts in random order
I started mine by having everyone put in their actual asset allocation ( percentages not dollars of course) as well as their proposed asset allocation if they were not already in one and had an idea of what they were planning.
Did the 30'seconds or somrountable introduction by everyone.
Had a handout with everyone's portfolio in it. Went around table, had group answer questions about portfolio, suggestions etc.
Had a specific talk prepared on a subject, say reits as an asset class, which I gave. I think I got another person to give a topic by second meeting. (always try to farm presentations out if possible, lessens work on you, and others may knows as much/more than you/different things than you, but it's often hard to get others to do,because it's like homework essentially, a chore).
Encouraged people to bring handouts for minitopics, of 5 minutes or so, that would be scheduled if people had them, followed by discussion. Basically encouraging lower cost to presenter content, than a more formal topic.
A second formal topic if possible.
Then a general discussion at end.
Basically, free floating discussion, with a format overlaying it.
Meetings lasted 2 hours about, at a restaurant.
Group size is important. 10 or so people is a good size for the ad hoc, discussion encouraged, and frequent round table format to address individual questions, that i used. Roundtable here means go to each person specifically in order. Much higher means a different format, or basically little round table, more formal presentations. Or necessitates breaking into subgroups, which implies dedicated help.
Assumed, and explicitly stated in initial email when they joined the group, that they were familiar with the basics, and/or accepted the basic boglehead premise, ie did not want a jim cramer investor coming to debate basic precepts at every meeting. Just my approach. Having someone wanting to debate the merits of say att vs Verizon, individual stock picking, wrong meeting.
I would try to aim for 6-10 people at meeting, which implies 12-20 on mailing list depending on interest.
Would not advertise unless needed a few more, so did not have to advertise much
Pm and introduce yourself to a few other leaders as another leader, to get on their email list. Steal their content ideas : )
Good luck : )