SEO efforts will help to increase PR of site but in that you would need to notice number of thing while you are working on build links like which links you are tying to get they should have quality and good PR.
If you want to increase your website PR instantly then doing the hard work on Forum posting, bookmarking, blog and article posting, classified and directory submission. Try to doing work on high PR sites.
It's strange to see that people still care about Pagerank, There is very high probability that google is going to drop the whole concept of Pagerank ( there haven't being any PR update since feb 2013).
I believe for better ranking , relevancy and content freshness are the key