1. Post relevance content and comments to sites with good Page Rank (blogs, forums, groups etc.)
2. Create good content -- add value (to your site and others).
3. Submit to directories, search engines, news group, social bookmarking etc.
4. Great keywords -- Use Google Adwords keyword tool
5. Social networking site like Facebook and Twitter
6. Article submissions
7. Link Building - to achieve greater visibility on the web
8. Affiliate Marketing
9. Email Marketing
10. Newsletter and Subscriptions - Great way to let the clients and customers in on the news.

Hope this helps