It might seem counter-intuitive, but the first thing to do upon joining a social media network is NOT to socialize, especially if you're a writer.
The first thing to do is to set up your profile and add some content.
Several times each week, I get a notice that somebody has started following me on Twitter, has circled me on Google+, or is following me on Pinterest. I go check out their profiles and input, and there is NO profile and their content is either non-existent or not viewable by anyone they haven't approved.
If I already know the person, face-to-face or online or by reputation, I return the following/circling. Otherwise, I pass.
And I'm easier than a lot of people: many will ignore an empty invitation, even if they know the person who wants to connect.
Because there are so many people out there who want to connect and who provide something and someone to connect TO.
You wouldn't invite somebody to dinner and, when they arrive hungry, tell them to sit down and wait while you run to the grocery and buy the ingredients for the meal, would you? Well, you might, but you'd have to be really REALLY good friends or a really really REALLY good cook. Also, you'd have to trust that somebody alone in your house, but that's another metaphor.
ANYWAY, when you join a new social network, fill out your profile and add a picture. Most people prefer to know what you look like, but people don't always get everything they want. Use your book cover, if you want to. If you can leave a link to your web site, be sure to do so. If you aren't provided a place to put that in, stick it into your About text.
Add some content:
On Twitter, retweet other people's tweets, if they're funny or helpful. Make your own statements. Tweet links to web sites. Boost friends. Tweet short reviews of movies, books, tv shows. Jump into conversations. Yesterday, I saw a tweet about a food I like, I commented on it, gave my take on it, was included in the conversation, and gained a new follower.
On Google+, you can do the same things by commenting on and sharing other people's posts, tossing out questions and opinions, posting links to websites, uploading your own photos, and linking to your own web posts (as I will this one). If you visit a web site with a G+ button on it, you can click that and add your own comment which will all be shared on Google+.
On Pinterest, after you've set up your profile, eliminate any boards you aren't going to use (if you aren't on Pinterest, when you get on, you'll understand what this means) and add some that you will use. Some of mine are My Books, Other People's Books, My pictures, Other People's Photographs, Cute Critters, Foodishness, Furnitures, Awesome Architectural Details. I have a board for each of my novels, where I put covers, trailers, people who could play characters, costumes, and more, but I also have content that people who aren't obsessed with my books would find interesting.
THEN, when you have content to offer, but certainly after you have a profile set up, start following people, circling people, following pinboards. You'll gain connections much faster that way.
Fantasies, mysteries, comedies, recipes