First on page optimization is important in website then you start off page SEO work social book marking is used to increase you web site traffic and article ,directory submission and other off page work is used to getting back links in your website
Start with posting quality content onto the site. Then you could submit the content to social networking sites as well as social bookmarking sites to help search engines index your web pages quickly. It will also drive traffic to your sites. Keep the submission as a routine job. The key to success is keep on doing it. It takes time, but will pay you back gradually. Then, think about building inbound link via posting with signature links on forums or commenting. If you are looking to improve the PR more quickly, start searching for quality blogs in relevant niches and get ready to invest money on buying links and guest pages.