Each group can originate its own format. A common one is to begin with a period, really before the formal meeting, when new members are instructed in the Prayer. Members are constantly encouraged to bring friends. The meeting then begins with a pe-riod of Centering in which the new members can participate. There is time for questions and sharing after the Prayer.
Some groups then have some input from a tape or a book.
Others prefer to turn to lectio and share the next Sunday's Gospel. It is good, with such groups, to have a fixed schedule for mov-ing along and concluding. Members can, of course, linger on, perhaps over refreshments, after the formal meeting is concluded. A group does best if it has a stable leader or leadership team. That does not mean that in the actual meeting the different mem-bers cannot take turns leading the Prayer.