Starting from 0 members is hard. We don’t discuss it enough. There are many ways to start an online community. It’s easier if you already have an audience. Darren Rowse, Ramit Sethi, Seth Godin etc can launch huge online communities in a matter of days (but they spent years building up that audience first). If you don't have engaged audience, this should help.
First decide who your community is for. Be specific. Identify real people you want in it. Then try to figure out what they really care about. Your community doesn’t have to be about your brand. It’s usually easier if it isn’t. Look at what your potential members do in their spare time, what do they spend their money on? What image do they try to portray to others? What do they talk about online?
You probably have a rival community too. Spend time there. What will make your community unique? What aren’t they doing well? Will your community be for more hardcore members or a broader audience? Will it be activist in making change or pacifist? Will it focus on single issues within the topic or geographical regions? What will be the focus of your community?
Next, begin reaching out to people (do this before deciding the platform). Talk to about 10 – 15 members about an idea for an awesome community for that subject. Ask them for their expertise to help develop a community. Ask them what their dream community would be like. Ask them if they want to help build it with you. Then put them on an e-mailing list with each other (or a forum).
Now have some conversations. Ask them things. Ask them what an awesome community must have. Ask them what what the biggest issues in their sector is. Ask them who should be in their community (and who shouldn't be). Make sure you have a stable base of 10 - 15 engaged members. This might take a week, it might take a month. But you need these stable members right now to catch the traffic later. This is how you seed a community.
Begin messaging these people individually. Invite them to ask other experts, celebrities or perfect contributors to join the community. You want the best people they know to join.. No promotion, direct referral only. Keep it tight. Make sure the conversations are being sustained. If someone goes missing, find out why then bring him back.
As you begin to reach 30 to 40 members, you will find that your mailing list is getting too busy to handle so many messages. It’s time to move elsewhere. Use something simple. Forums generally work best. Ning communities are cheap(ish). But there are other great platforms around too. Research a few. Facebook is simple, but risky. Ultimately, use a platform that your audience knows how to use.
Keep your focus on high engagement per member. Spend time talking to lots of members individually. Plan things together. Plan events. Write joint statements about relevant issues. Keep it invite only. Steady growth is good. Forget a launch day and celebrate milestones.
Begin discussing people in the community. Make sure people are talking about each other’s achievements. Peer groups are important. Gradually people will begin to hear about the community and join. Relax the invite-only status and let others apply to join the community.
Schedule your first meet-up. Make regular meetings a habit from the beginning of your community. Collaborate on a joint constitution for the community. Work together on a purpose (if you want your community to go that way). Ask others to help run the community. Appoint a new business volunteer to find ways to add value and make money from your community.
Once you have that steady base of members, ideally around 100, begin to promote it. Don’t grow too big, too fast. Write to relevant media and trade press. There are plenty of awesome promotional ideas. Just remember – after a point the level of participation decreases with every new member.
Finally, to keep participation incredibly high, begin to break your community apart. Highlight the most common topics and spin them off to their own areas within the community. Put the most active people in the topics in charge of these areas. Watch it grow. Arrange your first meet-ups and events. Invite guest speakers to join your community to discuss topics, work on a cause or achievement the community can aim for.