The way I go about it, with the niche side of the sub is that I look for some sample writings then approach the writer saying, "Hi there, I saw your story on the wiki or AO3. I was wondering if you've heard of (publication name)? I'm not a judge but I am community lead there and I think it would be worth a shot to submit a story for the next contest or open window. " They must earn their spot. They can ask for feedback on the server cause we're all happy to help and teach but there is no guarantee.