Use Social Media Sites
Facebook, twitter, Stumbleupon, G+, Digg or Reddit is some of social media can be used for this reason. To make it effective, not to publish the same link to every site and not to share them all your links at once as this deemed spamming and will get your account suspended permanently fast.
Yahoo Answers
Yahoo Answers can assist you to get a lot of traffic by answering inquiries off their site. If your respond are selected as the best one your respond is shown right below the inquiries given. Similar to blog post, question pages can reach higher search rankings over time, if you include your website URL the end of each answer, you are going to receive flood of new audiences.
Classified Ads
Classified Ads are alternative source of promotion that often gets overlooked. A site such as Craigslist is perfect for sharing your site and informing audiences what your site is all about.
Traditional Word of Mouth Method
The last tips at this post are word of mouth. Inform people you encounter about your website. Include your website address into business cards and distribute it personally. Share flyers on hectic location or on store that related to your sites niche.
That are all strategies you can implement to promote your website for free. Before you apply these strategies, make sure you elaborate more about the specific subject. More research you do personally can be handy, and will also ease you finds exactly what you need to promote website for free.