One of the most important part if you want to survive on Internet Marketing, is market exposure. You'll need tons of traffic and lot of people visiting your site before you can make some sale. Your site will be visited by a lot of people once they appeared on first page of google.
In order for your site to be able to compete with thousand other sites, you must do a lot of backlinking, especially from high PR sites. You can get those high PR sites list, by scrapping by your own...