As a writer, I would say that social media has to be one of the greatest tools I could use to get the word out about my work. When I published my first book, I used Facebook to announce book signings and updates about how the book was selling.
That was 2009, and I've been using social media now for a while now. Here are some benefits to using social media as a writer:
1. Getting the Word Out - Whenever I publish an e-book or a print book through Amazon Createspace, I post it here on my blog and then it is connected to Twitter and Facebook. I can watch my sales jump right after the announcement and it has had a profound effect on my sales.
2. Keeping in Touch - I sometimes get messages from readers who get in touch with me through Facebook, Twitter, Linked In, Tumblr or other web sites to do writing projects for them. This builds my writing platform and gives me a higher rating with literary agencies.
3. Building a Fan Base - I spend a lot of time (probably 20% of my "writing" time) blogging, twittering and commenting on other people's blogs, Facebook status and re-Tweeting. I post videos or articles that others have tweeted or posted that I find interesting. I try to tweet silly things now and again because I have a silly streak and love writing satire.
4. Free Advertising - I post every time I publish something new. I have a Kindle Single coming out soon, I am working on a post-apocalypse novel, I am writing a self-help book for a friend who is a motivational speaker. All of this will be on my blog, on Facebook and on Twitter. It is a guaranteed way to get hundreds of people to see your stuff without paying to have them see it.
5. Getting Feedback - Many of my Facebook and Twitter friends will write what they think about my new stuff after they read it. This can be used to improve my writing, post as a review on Amazon or wherever my book is sold, and generally help me understand how my readers see my work.
It all boils down to communication. If you are not willing to be a communicator and share ideas with others and let them help you become a better writer, then you shouldn't be writing. Above all, social media is a great way for a writer to find a community that supports their efforts, encourages them and points out the faults that make us un-successful.