I do this for a few sublemmys like !nasa@lemmy.world and !esa@feddit.nl. I view it as keeping communities on “life support” until Lemmy grows a bit more.

One of the best practices I can think of is to cross-post a post with text in the body (important) from a small sublemmy to a large sublemmy. This creates a link to the original post on the smaller community, and gives it some visibility.