What is the best way to bring people to an online community through social media?

You have to provide a content that is short, light but interesting. Its all about creativity and putting your self in the reader's position. If your goal is selling a product through an online community, the content should not be 100% ads, it should bring people around a something that would help them daily.

Ex: if you are selling beauty products, why not create a community for the ladies so they can share their beauty secrets and experiences, and than use it to slide in some ads.

In journalism, they tell you to be very colorful, which basically means that your stories need to be very descriptive and explanatory.

You content should be a narrative - a transmedia story that carries the same intended message accross multiple channels online. 

Similarly, when it comes to social media, the best best way is to use the mix if the following:

- Engagement posts

- Questions

- Constructive industry critciquing

- Content curation

 - Content aggregation

- Use lots of video

- Use a photo with non-repetitive captions

- Short texts

- Properly formulated hashtag strategy based on the user flow you get from Google Analytics

- contests to drive conversation and conversion

The answer is certainly online

To connect and reach maximum people on social media creativity round your posts/updates. More interactive your posts will be, more people will inclind to join the community. Define your rules to limit the range of posts but dont make it too bossy too.

Innovative ideas of common interest always attractes people like food, books, movie review, technology, habit activities, health etc etc. Communities which are more technicals like medical, research and all they dont attract people much untill and unless you add some masala to it. OR even if its too technical but the presentation of the crucks should me decorative so that readers enjoy the post.

Quiz, jargons, conversational post also increase your reach and if you add some surprize element then its like icing on the cake, people will not only participate but they ll also pull people of same interest.