Pass around a sign-up sheet before class. Find people you are comfortable with and who share some of your academic goals. Limit to five or six people. Test each other by asking questions. Practice teaching each other.
Teaching is a great way to learn something.
Compare notes to make sure you all heard the same thing in class and that you all recorded the important information. Conduct open-ended discussions and debates designed to produce understanding and insight. Select the items from the above list or create other activities that you will do as a group. Set approximate times for each agenda item and determine a quitting time. End each meeting with assignments for each member.