In the Science of Persuasion, the participants discuss 6 keys to persuading readers:
In a blog, reciprocity is key; you have to have something specific to offer readers if you want readers to follow you and comment on your work. It can be a juicy secret, the key to dropping pounds quickly, a cure for beating anxiety, or one of a million other examples, but you must hold out the apple for the reader and hope that he or she will bite.
I think the most successful blogs rely on consistency. Pick a theme and stick to it. I'm reminded of Julia Powell's blog; she had something new to share about her cooking project every single day. I think bloggers that are too scattershot tend to frustrate readers. Mandyfish varies widely in her topics, but she's always funny; her quirky sense of humor keeps readers coming back for more. Consensus plays a part here too; if I see a Facebook post from a friend who has posted an intriguing blog post, I'm much more likely to not only read the blog post, but to poke around the blog site as well. Social media helps to proliferate blogs (and a whole lot of other articles, ads, goods, services, etc.) like wildfire largely because of consensus.
Bloggers must develop a voice, and that voice has to be likable, for the most part. If, as William Zinsser notes, bloggers descend into the depths of whining and overexposure, they may see a spike in readers for a day, a week, or a month, but they will lack the longevity needed to sustain a blog for the long term. No one likes an Debbie Downer.
Authority is mostly irrelevant in a blog. Bloggers (like myself) often use pseudonyms, and the details of our backgrounds are obscured, invented, or buried entirely. I won't allow my students to use blogs for academic research because so often the blogger's identity is shrouded in mystery, and we have no way of knowing if he or she is credible. Without that ethos, I am always a bit wary reading a blog (at least for academic work).
Scarcity doesn't even apply to blogs. There are a million blogs about a million topics, and if you check out WordPress, they claim that 50,000 new sites are created every day.
That last statistic really gives me pause. I'm just one lonely fish out here in a limitless pond.