get lots of high pr links to your site and your pr will increase, you can buy them or you can get them the way you want, the more high pr links to your site the better.
I never believed on fastest way. Step by step is better Best content first, then look for quality site with high PR for link echange.
You should try to get backlinks for different sources, article submission, directory submission, and paid links.
sudden surge of backlinks can be a problem....blog commenting on dofollow blogs can get you backlinks as well as traffic.....go here http://forums.digitalpoint.com/forumdisplay.php?f=65 and give your website for submission....this is very good for building nice and steady backlinks for a longrun using whitehat method
The ONLY way to raise your PR is to get backlinks from higher pageranked pages. Ie. 1000 PR0 backlinks will get you a PR0, PR1 at best. 1 PR7 link will get you a PR6. I've seen this happen - twice.
Buy a Yahoo Directory link and then don't ever worry about PR ever again. Rule of measure that you might want to consider..... {X)PR = $0.00 Unless you sell links or own a directory its a useless imaginary number conjured by Google to keep webmasters chasing their tails....