You got to write articles and submit them to article directories in order to get your site known. The more your write the more backlinks you get and the higher your rankings will go. Also, you got to write good articles with the right keywords in the articles.
look for article directories with good PR and alexa traffic, as well that are DOFOLLOW. please consider this list here http://www.vretoolbar.com/articles/directories.php
You could put your website on your siggy with it's proper keywords. Also Ezinearticles is one of the best articles to write for.
To improve site ranking, First readout Google guidelines on SEO. It will help you a lot to the basic things. Then start to put on news, articles etc on your website Submit it on different websites like digg etc.. For higher ranking, you have to generate user traffic on your blog / website. Social marketing is also a great way to generate traffic.
First make your site seo friendly. Then do link building activities for improving ranking. Article submission is very useful from all other activities and you should use do follow and high pr directories for that.