Growing a New Subreddit

I'm the moderator of a new subreddit r/JacksonvilleNCr4r. What's the best way to grow the subreddit? I would like to post in other subs to tell people about it, but I'm concerned that people might consider it self-promotion. Especially because it's a R4R sub, it's important to have a critical mass of people join, so that it actually becomes useful. Any suggestions? (desktop)