PR depends on lots of factors like your site on page and off page, keyword density your site theme etc.
Try doing some social networking submissions from the sites given under addthis.com widget. Also make sure you comment on high rated forums and blogs of your own niche. Then try out some link exchanges, but go for 3 way link exchanges, instead of a reciprocal link exchange which might not get that much link juice. Above all you can buy links on high PR sites anytime to get a quick pagerank increase
Who cares about PR, Aman. Focus on developing your website - through quality content - quality backlinks - and your PR will go up - depending on how quality you do things.
The most effective way is to get backlinks from high PR sites. PR 3 and up would be preferable. Getting a lot of PR n/a or PR 0 backlinks will not be as useful and may adversely effect your PR in the long run.