I created a web-based utility. That on its own isn't much to bring people in (or even back). I quickly found out that it was important to keep the site updated

I created a web-based utility. That on its own isn't much to bring people in (or even back). I quickly found out that it was important to keep the site updated regularly with fixes and new features. Announcements of new changes would be published to sites like HN or Slashdot as press releases. So I wasn't really posting things like "hey, check out my site, it does X!" It was more like "How Y can integrate into X" or "trending stats on Z, provided by X". That sort of thing. It was also crucial to have a mailing list in place where people could sign up easily. That way, I could reach the users directly without worrying about trying to get a post approved or posted onto a third party's site. The other benefit is that, if people liked my updates, they would sometimes go out of their way to repost my updates on sites that they visit that weren't even on my radar. Communications would always try to tie back into relevant problems or interests of our userbase's demographic, but referring to the site as a potential solution. So there's value for readers, even if they aren't my users. Just keep trying new things and new audiences. Things will click into place as you go if you're delivering quality and as long as you don't stop.