I have a couple of friends who only talk about themselves and their achievements. I love them dearly but really, they are awful bores. I don't introduce them to my other friends and I don't really listen to what they say.
On the other hand I have friends who tell me about their friends, about gossip, and ideas, and news, and politics and life..., and then they talk about themselves. And by then I am ready to listen and share all the interesting bits with my world
This is everyday real-world social ability, but it transfers pretty directly to social media. Guess that's why they call it social.But it doesn't explain why lots of brands still use social media to talk about themselves.
I like the ones that listen to their users, interact at an individual level and that talk about interesting stuff first and themselves second.
In other words have fun, or are useful, or at least interesting rather than treating each buzz, tweet and post as a branded broadcast opportunity.
I like the @cocacola stream for this. Even though I don't like coke. And the @virginatlantic is useful, and very personal. @microsoft - your tweets seem somewhat self-obsessed. (You too @Google! - though not quite as bad)