At the risk of sounding sarcastic and obvious, write good articles about something interesting and that certainly is a good start!
You need a solid blogging platform that is optimised for the search engines and you should post to twitter/facebook with the latest article. Make sure you are blogging at a regular and sensible interval and another avenue is to find a blog such as smashing magazine, for your particular subject, that has a network of blogs you can apply to join. Guest blogging for other blogs is also a good way to get some exposure.
Traffic doesn't mean anything if they leave the site due to poor content, building a solid site with good content is a far better time investment that focusing on getting traffic.
Edit: Beaten to it!