The second step is to define the goals and reasons for the group. If you all are in the same field, the writing group may be a place to extend your arguments or hone your thinking. If you all are in different fields (and writing groups work well with either kind of configuration), your writing group may be more of a place to polish your work, or to build in accountability. It might be difficult to generate relevant feedback if others in your group are not well versed in the issues of your topic.