Having a strong presence on social media is the easiest way to network with other authors, readers, potential publishers and agents. Granted it's not an over night success and may take you a long time to build a network of friends. I have been using Twitter since 2009 and have found it the best way to meet likeminded people from all over the world.
I will focus on Twitter in this posting since for me it's the easiest way to build a network.
The rules are simple for Twitter, your posts have to be in a 140 characters, which makes it a chore to be creative with your posts. #hashtags locks your tweets, for people to find, if searching for the focus of your tweet. So make your tweets diect to the point and from time to time fun. Be engaging and smart and you'll find people retweeting your posts, and the more retweets the more people discover you.
Speaking of retweets (RT), this is the best way to get people's attention, most of the time (not all of the time) you'll receive a follow from another author, or reader because of your RT. Thank them for the RT and try to engage in conversation.
A conversation may be something simple, comment on a tweet, be polite and make sure you thank them for talking to you. Keep your presence known with more RT's and before you know it, your network has begun.
Following people: Follow those who write what you do, don't expect a follow back, but before you follow someone, look at there following, followers ratios. If the numbers are with in a few hundred or so, it's a good bet they follow back. If you follow people like Stephen King, didn't expect a follow back. They receive hundreds if not thousands a week. But treat them as you would anyone else. After all they are as human as we are.
Create lists: Twitter has a cool feature in creating lists, this is a great way to simplify those people you want to keep in contact with to continue that conversation. Remember all social media is a great way to build a fan base and author list.
Be polite even if you meet people who aren't (and you will). The best way to handle that is to leave them alone, don't answer them and take the high ground. The more use of social media (like Twitter and Facebook) you will find both sides of the coin. The good and the bad, as in life.