In order to increase page rank of website, you need to post your content on High PR niche sites, it will get you high quality backlinks and your website PR will increase..
Tips to improve the page rank
1.Get Incoming Links from High Quality Related Sites- connect your site with other high rated website or blogs.
2.Write original content.: - do not copy paste any content from one site to yours
3.Write Great Content: make sure your site content is great and unique. If you write great content people will automatically link to your site which will increase your site rank.
4.SEO helps to ensure that a site is accessible to a search engine and improves the chances that the site will be found by the search engine. Search Engine Visibility is helps to increase your page rank.
Page Rank concept is dead now. I think you should not concentrate on PR now onwards. Domain authority and Page authority matters more according to Google.
Concentrate unique content.Submission on high PR sites and build quality link. And many more other activities for increase your page rank like :
Article Submission
Social bookmarking
Classified posting
Blog commenting
Forum posting etc.
Pagerank is old technology. It seems that higher page rank doesnt guarantee you to have better visibility on google. I believe that the most important thing is the content of your site.