Ask Lemmy

1. Determine the focus and point of the community. Write the description according to that so users know what to post.
2. Set up rules that go along with the focus. If your community is about Pikachu and someone posts cat pictures, that's something that should probably be removed.
3. Post some content but not too much. Don't want to make this your personal blog. You want others to participate.
4. Advertise it appropriately. Post to new communities. When there is another post and comments discussing your topic, mention that you have a community dedicated to it.

Getting a new community up and running is actually pretty difficult. Many of mine on reddit failed. But a few of them took off.