There are a few ways to go about getting higher PR
1st buy links from high ranked sites that don't just link to everyone and don't have many links going out so they can pass some of there PR juice on to you they should be related to your websites subject this is important to give you some authority
2nd update your site continusly with information that other sites will link back to make your site an authoritive site
get listed in a few directories here are 2 very important ones
Yahoo! ODP - Open Directory Project
Give it some time Google does not update PR every day infact now adays they do it less and less and PR is less important then it used to be so don't spend all your time on PR I prefer a PR0 site that is making me bucoo bucks off lots of free search engine traffic then a PR6 site that is making me almost nothing or does not get as much search engine traffic PR IS NO LONGER THE MOST IMPORTANT THING TO GETTING SEARCH ENGINE TRAFFIC and again give it some time google takes a while to update PR now adays