I would say really do some analysis on your audience. I found these questions helps: What is going interesting or engaging about my content / group to other peo

I would say really do some analysis on your audience. I found these questions helps: What is going interesting or engaging about my content / group to other people? E.g. is it going to get them funding, network contacts, ideas for their business, problem solving Also consider that their maybe already be some good groups for this content on Linked-in, Meetups etc. If you have some form of this already What about my content / group are or willl be people responding to? How can I use that to get more attention? Then do some analysis of the pro's and cons of each group based on your analysis and requirements e.g. I was reading that Yahoo groups has the largest number of people currently, Facebook groups is new and ideally suited if you want primarily have friends on Facebook contributing. I also like the idea of linked in groups if you want this to primarily be a professional focused network