Small groups matter in the church. Regardless of a church’s size, the small group is a place of teaching, fellowship, prayer, and pastoral care. The adage, “A church must grow smaller as it grows larger” is more than a church growth cliché; it is a principle of Great Commission growth.

Many small groups, though, turn inwardly. Here are some ways to strengthen the outward focus of your church’s small group ministry.

1. Be clear about the purpose of the group. Every small group exists for some reason. Some focus on evangelism. Others emphasize discipleship. Some are short-term focused studies, while others have an ongoing curriculum. The problem is that many small group leaders and participants don’t think about, aren’t clear about, or even disagree about the group’s purpose. Unfocused small groups—like unfocused churches—often plateau or decline.
2. Make sure the teachers/facilitators are good teachers. This point might seem obvious, but I cannot make this statement strongly enough: bad teachers/facilitators produce weak small groups. Being unprepared or boring is inexcusable—especially if the goal of the small group is Bible teaching. Don’t be surprised if groups with poor leaders don’t grow.
3. Enlist teachers/facilitators who want to multiply the group. The leader’s influence here is huge. If leaders want only to grow a crowd to hear them teach, the potential for producing kingdom growth will ultimately be weakened. If the goals of a leader are to grow a group, raise up new leaders, and send them out to reach others, the group will likely catch that vision.
4. Train teachers/facilitators to think as guests. No longer can we assume that guests—or group members, for that matter—have even basic biblical knowledge. Guests may not understand our Christian terms or denominational lingo. The best teachers/facilitators recognize these truths and adjust their teaching accordingly by explaining basics and defining terms.
5. Be aware of the 80% percent rule. At least in North American culture, physical space matters. When a group reaches 80% of its space capacity, numerical growth is likely to plateau or decline. Outreach often becomes less a concern when group members perceive the space is already full.
6. Use nametags. Some groups provide a nametag only for guests. I understand that thinking, but it actually puts the guest at a disadvantage. Others may call her name, but she cannot respond in kind if the “regulars” aren’t also wearing nametags. At the same time, the group that says, “We don’t need nametags because we already know everybody” is likely not thinking about growth.
7. If your group uses written curriculum, have extra copies available for guests. Suppose new guests attend, but you have no copies of the study for them. You have essentially said to them, “We weren’t thinking about the possibility of others coming. We weren’t prepared for you.” A lack of material for guests indicates a lack of expectation among the group members.
8. Train a pastoral care team for each small group. Get ready for growth by putting a small group pastoral care infrastructure in place. Small groups do not automatically follow up with and care for their members. The cracks through which members fall are sometimes quite wide. A strong pastoral care team (perhaps as few as two people) can help correct this problem. No small group member should be absent without follow-up, ill without care, or needy without assistance.
9. Enlist an outreach leader for each small group. Few small groups default into an outward focus. Instead, they turn inwardly, often without recognizing the resulting stagnation. A strong outreach leader can continually remind the group of the need to do personal evangelism and guest follow-up. Intentionality is important, and the outreach leader can lead in developing a strategic growth plan.
10. Lead groups to pray for people who have never attended.  We most often pray for people who regularly attend—that is, for those we know and see. The most Great Commission-focused small groups, though, pray also for those they are trying to reach.

A quick review of these suggestions should show you this point: the one who leads the small group matters. Good teachers will teach anywhere. They will take bad curriculum and make it interesting. They will figure out how to address a group member who dominates discussion. They will enlist and organize other members for outreach and follow-up. They will lead the group to multiply itself. Getting the right leaders will take your church a long way toward growing effective small groups.

Taken From http://thomrainer.com/2013/04/23/ten-ways-to-grow-a-small-group/