Be honest: how many of your followers are writers or authors and how many do you follow because they are writers or authors? My blind guess would be about 95%. I admit, when I started out with social networking on Facebook, all I did was trying to gather 'friends' and I envied those who had over 1000 on their list. Same with Twitter, I connected with anyone whose name I vaguely knew.
It became clear very soon that having all those writer friends on facebook didn't really bring me much other than having their constant promotion in my face as soon as they self-published. I started to delete those I never really talked to and kept those who are dear to me and with whom I have interesting, funny and informative exchanges.
On Twitter, I stopped following back. Instead I take a look at the profiles and blogs (if link provided) and decide then if they are 'worth' to follow. The problem is that I'm an author myself, so my tweets or the tweets of my followers will most likely be about writing or the books. It's preaching to the choir. There's no need to gather as many followers as possible, because only if your followers retweet your tweet, you'll have more exposure and that only if they have plenty of followers themselves. I have a few followers who have over 30k people following them, we never talk, they never retweet my tweets so I'm wondering what's the point of following them?
I observed that I'm gathering new followers (mostly writers) and when I visit their profiles and they don't interest me enough to cause me to follow back, they'll unfollow me a little bit later. We never exhanged a word. Which means, they didn't follow me because they found my tweets or profile interesting, they followed me in order to get a follow back. Well, no, I don't see the point.
Please don't get me wrong, I love the people I connect with, they are carefully selected -- at least those who'll stay in my list as I'm slowly going to clean it up -- and I'm having good conversations with many of them. Sometimes we don't talk for ages, but that's a Twitter thing, time differences, life, etc., but I only follow those who will catch my eye, be it due to their profile, their blog/website or because of our exchange.
To up your 'presence' write interesting blog posts, informative, educating, be versatile; something that'll make you stop and read another person's blog. Write about what you know, blog regularly and be selective with the people you connect with. A following of 4k or more won't help you if they only follow you because you follow them.
Have you noticed that a large following helped your exposure? I'd like to know about.