When I contacted Charlie McDowell for an interview regarding the success of his blog, Dear Girls Above Me (DGAM), the goal was to glean tips for gathering social media fans and followers. Since its launch in December 2009, DGAM has garnered nearly 25,000 followers on Twitter and more than 11,000 on Facebook. Surely, then, McDowell would have some handy marketing advice.

As it turns out, no. Nonetheless, there are lessons to be learned from the rapid, stealthy growth of DGAM.

McDowell didn’t set out to become a cult hero with DGAM. Prior to December, the comedy writer/nascent filmmaker “had 10 Twitter followers,” he says. “No one cared.” Then two young women moved into the apartment above his. What with the building’s odd acoustics and the fact that the new neighbors were apparently incapable of speaking at a moderate volume, McDowell was forced to overhear many of their conversations.

And these conversations weren’t about quantum physics or Nietzsche’s Ubermensch theory. After one 40-minute conversation that began at 7:30 a.m. and focused on what they would do that day if it rained, McDowell decided to vent by posting on his Twitter feed imaginary letters to the women above. (“Dear Girls Above Me, if I’m banging a broom on the ceiling for you to shut up and you aren’t able to hear me, it means you’re being too loud”; “Dear Girls Above Me, talking about how it’s raining for 37 mins can be simplified to ‘Hey, it’s raining outside.’”)

“At the end of the day I had 15 followers, and a few retweeted the posts, which is how I learned about retweeting,” McDowell recalls.

McDowell quickly settled on posting one such “letter” to his neighbors each weekday. His following grew exclusively by word of mouth, leading him to launch a Web page and a Facebook page. He’s done absolutely no marketing, however, to grow his fan base. Nor has he managed to monetize DGAM yet, although he is developing both a book and a TV pilot inspired by his neighbors.

So, what can we as marketers learn from this?

1) While you can control what you share via social media, you cannot control what other participants in social media share. We all know of people and organizations that created videos or Websites whose sole purpose was to attract attention—and that nonetheless failed to attract attention. One reason may be that people on Twitter, Facebook, and other social networks are by now skeptical and savvy enough to sense when an organization’s efforts at socializing and sharing are nothing more than efforts to reap revenue. Or as McDowell succinctly puts it, “People smell bullshit.” Which leads us to…

2) Be authentic. Sure, it’s trendy to be eco-conscious, and going green can be good for business. But if environment awareness has never been part of your brand’s DNA, and if no one at your company is passionate about it, then suddenly blogging about it will most likely come across as inauthentic, and will do more harm than good to your company’s standing.

“I didn’t do this to make a show or get a huge following on Twitter,” McDowell says. “That wasn’t in my consciousness. For me it was a very personal situation that was going on, so it came out very naturally. The best stuff comes out of what’s real.”

3) Consistency is your friend. McDowell posts once each weekday, at roughly the same time of day, and in the same format. His fans have come to expect, and anticipate, his daily entry. If he suddenly veered off into, say, rants about infomercials or impassioned pleas to stop deer hunting, his audience would be confused, and many would no doubt be dismayed. Ditto if he stopped posting for a week without notice. Once you’ve set expectations, either explicitly or implicitly, you’ve got to deliver.

4) Keep an eye on opportunities for leveraging what you’ve got. For McDowell, that translates to a possible book and TV series. For the rest of us, it could be a dedicated newsletter should a particular blog topic take off or a product extension should demand for certain items exceed expectations.

5) Only connect. “The people that do follow [DGAM] are real diehard fans, I guess you can say,” McDowell says. Indeed, some of his followers have sent photos of hats and T-shirts they’ve adorned with one-liners from his posts, and they regularly post comments on his Facebook wall.

“What it really represents,” McDowell says, speaking of both DGAM and the response to it, “and what we’re all striving for is a connection. Our genders may be completely different and our interests, but at the end of the day, all we really want is a connection.”