Everyone gives a lot of importance to Google PR and they should as the higher the PR(Page Rank) the more often your site will be crawled by google bots increasing chances to see see your site on top on related keywords in search engine.

Google PR is all about links. Google gives special preference to natural links. The more links pointing to your site the higher your site PR gets and the more links pointing from your site the less PR you get. So basically you want more of one way links pointing to your site with high pr so that your sites PR are raised. Getting one way links which are based on your site's theme can be of big help, which are difficult to get but are worth the effort.

Here i'll tell you something about linking.

Linking is tough. So don't expect quick results you have to be patient and there is lot of hard work.
1.) Stop clicking on any crapy advertisement which says "I made $1,000+ in one week!" "I made PR 5 in one-two weeks!" These things never ever happen they are all lies and if they were to happen they would not be sharing it with you.
2.) Don't waste your time submitting your site to those same old lame directories which does not even bother to add your link to their categories and you wait and watch for months and months.
3.)Try to limit yourself in link exchange. Previously it would work but now as the search engines have noticed with mutual understand website owners are sharing eachothers link. They started giving less importance to reciprocal links.
4.)Try commenting in blogs they can give you heavy traffic. You get few hits for articles written by you but commenting on articles and blog post provides even heavier traffic.

Please don't just try dumping all the links but work for it and you will be rewarded by google. Use do-follow links to quality sites.