Twitter can be an amazing tool to keep readers of your blog updated.
That is the main reason why they go together so well, see only the people who choose to be updated are.
As you might have noticed all big websites out there have the option to follow them on Twitter.
Once you get a good amount of followers, Twitter can be a pretty good source of traffic.
I would recommend also getting a Twitter plugin for your blog, so the updates you post on Twitter are automatically posted on your blog.
You want to make sure have a separate Twitter account specifically for your blog.
This way you can inform the people who follow of the current news on your blog and everyone would be interested because they came from your site and decided to follow you on Twitter.
The key to actually getting traffic from Twitter is really simple, all you have to do is communicate with people.
Really just talk to people who are interested in the same niche as you and you should get some quality traffic.
I mean really talk to anyone on Twitter, about anything! That is why it is very important to be interested in your niche (the subject you have chose to write about on your blog) and know at least some good information about it, if not you could always learn.
But as long as you are interested! But anyway, you have to communicate a lot about your topic, write about it, learn about it, etc.