There's no better way to gain credibility than write useful articles in front of your target audience. But what if you're site is brand new and you have no audience?
Find someone who does!
Many blogs and websites increase their content and gain popularity by finding 3rd party contributors. Think about it. It's a win-win. The owner of the site gets a break from writing, and the authors who
are featured get some added exposure.
Search for sites and blogs within your niche and contact the Webmasters to see if they allow guest contributors. Have a few sample articles ready to display in case they ask.
Lesson #7 : Traffic Optimization - Publish a Newsletter