Get people into a routine. Decide on the purposes of the group. Group members share screenwriting knowledge and provide friendly, constructive critiques of each other's script, treatment, or outline. Members also exchange screenwriting books, magazines, tapes, and their experiences finding agents and marketing scripts. Some groups focus on one or two writers per session.
Some groups require members to send the work to others in advance of the meetings.
It's often profitable to read scenes aloud at the meeting itself and evaluate them on the spot, or address writing ideas and specific writing problems. Make sure critiquing sessions do not turn into slugfests. Writers should avoid a defensive posture. Listen carefully, avoid speaking, take the advice seriously, but remember that you are the writer of your script. Criticism should be given constructively.