To increase PR, before you have to increase your website backlinks, so you have to focus on backlinks for this you have to follow some best off-page techniques..i.e.:
* Link Wheel
* Blog Commenting
* Forum Commenting
* Web 2.0
* Ads Posting through Classifieds
* Press Release
* Profile Linking
* Local Business Listing
* Social Bookmarking
* High PR Directory Submission
* Article Submission
* Guest Posting