OK -- here are ideas on the most basic keys to effectiveness:
0. Serve the church - This should be understood; but it's better to articulate it because, unfortunately, the minority of church missions teams have this orientation. Missions ministry is not "turf" to defend. It is not a holy area reserved for the gnostic initiated. The whole purpose of delegating the special interest of missions ministry to a team on behalf of the congregation is that the missions team is to serve and represent the best needs and direction of the church in the area of missions. The whole church needs to participate and be involved in missions. The MT's job is to work toward that end, that every participant in the church becomes an involved world Christian. The MT's goal is to see that God's glory and the gospel of Jesus Christ proclaimed to all nations is at the core of every ministry of the church and on the heart of every member.
1. Meet regularly - It is amazing to me that people wonder why their missions team isn't very effective, yet they only meet a few times a year, usually when the pressure of a missions event forces them to meet. Monthly is good.
2. Select the right people - Don't accommodate volunteers, just because they volunteer. Think about specific skills and effective people you need and go after them. Don't neglect to get a mix of age, experience, newness to your church, etc.
3. Train team members - At minimum, give reading assignments on the basic information and concepts every team member should know. Mutually common training, e.g. the Perspectives course, provide a sound platform to keeping everyone on the same page and building into their lives.
4. Specialize and delegate - The work of an effective Missions Team takes place largely outside of the Team meeting times. Assign individual MT members to specific task areas, e.g. education, personnel, funding, short-term trips, prayer, and use the team meetings for reports and tweaking direction. Empower the MT members to recruit help from outside the team to help them do their task area work.
5. Become a team - This speaks to ethos or culture. As you grow and work together, it should become natural that the team cares for, prays for, and helps its own members. It also implies that you get into each others lives a bit; there is mutual discipleship and spiritual accountability going on. A great team environment and mutual trust go a long way toward effectiveness.
6. Communicate - Needless to say, this is always a key ingredient anytime there are people involved. Have someone keep notes and distribute them (yea for email!) as soon after the meeting as possible. Get an agenda out BEFORE the meeting to everyone involved. Keep agenda surprises to a minimum (non-existent?). Communicate decisions to everyone affected up and down the chain of command - church leadership, church/mission treasurer, missionaries, congregation, teachers, small group leaders, candidates, participants, etc.
7. Evaluate - Give every MT member opportunity and encouragement to question, challenge, refine, and be creative in finding the best way to serve your church in the area of missions. Routinely include a post-event evaluation as part of every major missions event or activity. Learn and build on the past, but don't worship it!
What are your keys?