How do people build NSFW subreddits?

Doesn't seem like a particularly hard task to fill a subreddit full of high quality content. It's all over the internet. But how do you get people to actually come visit? What are the most common techniques?

I thought about message ads. But that would likely get the subreddit canned by the mods. In fact most of my ideas would get the subreddit canned quickly.

Thought about growing it from some other source of traffic. Like some forum. But don't really know of any.

Thank you ahead of time.

Get popular posts from other popular nsfw subreddits, post them on your subreddit, crospost back to the original subreddits. This can get you a lot of traffic.