Once you engage with social networking, you will be engaged with those communities. Share your thoughts relative to your blog topic with the people in your community. Comment on other bloggers' blogs and left your link there. As time passes, you will get more and more traffic through these networking sites.
There are different applications on Facebook like Networked blogs. You must join these kind of communities and establish relationships with other bloggers. You must make offers like follow and comment on my blog. By this you will get traffic to your blog
Twitter is really good site to promote your business and your sites. Make friends on Twitter and have discussions with them. Tweet daily and give your link there also. Tweet useful things so that people get attracted to your tweets. Always promote your posts following with your URL. Tweet like follow me , i will follow you back. By this you will get more and more followers on twitter.
Publish your latest posts on digg and myspace also. Stay in touch with other bloggers and have discussions with them. To be successful you have to be good marketer too.
Happy blogging...