For about 3 years I have been a part of a local writers group (Montague Library Writers Guild). The group has never gone above about 10 in attendance and folks have come and gone over the years. Part of the challenge is to find an identity and set of activities that draws and holds members.
Some writing groups are much more literary that ours. One group put out a book with Japanese art on the cover and was, I believe, focused on short Haiku-style poetry (I had to Google to find out the word since it is not one I use often). I believe the group is closely related to a university community–a source of highly educated members. We decided early on to develop a book as well, but went in a different direction. The book was a collection of local Island (PEI) stories. This had two advantages: 1) The writing was about things the individual authors already knew well–personal experiences and local history. 2) There would be a clear market for the books in local gift shops since the topic would be of interest to tourists as well as residents. The book(s) sold fairly well (up to a few hundred of each of the 3 books).
But people moved on and the interests changed. I had hoped to have regular teaching parts to the monthly meetings but that seemed to peter out. The direction that has been most effective is to have each attendee who wishes read a short bit of their work and take comments and suggestions. And the meetings went to alternate weeks. More frequent seems to be working better–easier to remember and allows regular feedback as well as encouraging regular writing.
Almost everything takes some experimentation to find a formula that works. Perhaps we are getting closer.