Are we speaking only about SEO here or about all the ways to generate traffic to a website?

If we're speaking about SEO the best way is to start blogging and by this I mean as much as possible. Every single blog post is a new content, a new page that can be found by the search engines (and your customers as well).

You might also think about creating ebooks. You will not only generate traffic with them but also leads which you can nurture to become your customers.

Start building your communities on Facebook, Twitter, LinkedIn, Google+, Pinterest and share your blog posts there. Engage in conversations and provide value to others.

Use social sharing websites like Reddit, Stumbleupon and Digg.

A great tool for linkbuilding and PR/Social media exposure is BuzzStream http://www.buzzstream.com/ You might want to check it out.

Let me know if you need any more help with building traffic to your website.