Community Slack can be difficult. It's free and one of the best UIs and useful tools in recent history of apps. Yet there is a challenge in keeping users interested and keep them coming back.
SSG started as a blog at startupstudygroup.com which then experimented with an email list and a couple of SSG members recommended Slack so I tested in January 2015 with a handful of users and here we are in November 2015 with 2365 "active" users. https://ssg-slack.herokuapp.com shows 2453 and the gap is due to inactive users.
Some thoughts on what worked for SSG:
1. Creator is obsessed with the idea. For SSG, the idea is a free community for startup founders and investors in a positive environment that will outperform private exclusive networks.
2. Goal is clear. With a clearly stated goal, users who get the message will evangelize the group. There will be stars with extraordinary skills who will take the community to new levels.
3. Golden rule. Treat users like you want to be treated. Occasionally, there will be spammers and a**holes and it's up to the owners and admins to deal with them effectively -- ban them. We are not recreating Internet with BS that comes with it. We are creating something better.
4. Ignore noise. Everyone has a comment about how you should raise your kids. Some are good words but most are not worth implementing immediately.
5. Keep at it. The idea has be so great that you can't stop working on it. Most people will not get it and that is ok. You know deep inside that this product has to exist.
6. Puns & memes. Humor in general work well. @alwaysagoodday1 for Air Squats (TM) and @webhat for the basilisk.
Some awesome members at SSG who you should consult if building up a Slack community (so follow them on Twitter to engage): @webat @geeky_yang @nuclearpengy @indymike