It looks like everyone agrees, get more incoming links. Actually, more links would probably solve most webmaster problems. Bompa
Well achieving pr 3 or 4 is easy thing, if google keep updating pr after every three months, The difficult thing is achieving pr4+ for your site, and there is just one way to increase your pr that high is get back links from sites those have high pr like pr5+ now its depend on you how you are getting them,
Page rank is calculated based on the number of back links that you are getting. In order to get back links, engaging on the techniques such as blog commenting, forum posting, classified ads, press release, online groups, article and directory submissions, link exchange and social bookmarking helps. Note: Get back links on relevant and DoFollow sites.
Hi dear, you know for Page rank you should try good pr directory submission as well as good pr article submit. after 2-3 month you will see you page rank jumpp.