If you want to increase PR, then you simply have to start focusing your efforts on building backlinks to your site. The 2 most important factors to increase your page rank is this:
1. Get High PR Sites To Link To You
2. Getting a Large Volume Of Backlinks
There's a lot of other factors that many SEO experts claim to have a positive impact on your PR. Some of them like getting links from ".edu" sites might have some value, but for the most part focusing on quality and quantity links will get you the best results. It's always wise to build both quality and quantity links. As a rule of thumb, you can split your link building efforts 60/40 with 60% of your time focused on quality links and 40% on building quantity links.

