Top 10 DoFollow High PR Article Submission Sites For Backlinks:
* http://www.squidoo.com/
* http://hubpages.com/
* http://ezinearticles.com/
* http://www.gather.com/
* http://www.selfgrowth.com/
* http://goarticles.com/
* http://www.brighthub.com/
* http://www.articlesbase.com/
* http://www.articlecity.com/
* http://www.sooperarticles.com/

1.Forum posting
2.Blog posting
3.Article submission

You can use article,forum, blog and web 2.0 for getting do-follow backlinks.

1.Forum posting
2.Blog posting
3.Article submission
4.Form social

Use Directory Submission sites and build high PR links

You can get do follow links on sites like Q&A, Blog comments, Edu, Gov Forums, Dmoz, Google +, Web 2.0 Properties, Web 2.0 profiles to name a few.