The best advice I would give you is be a regular commentator in forums like DP and WF, you will atleast get a PR1 very easily. However personal opinion pagerank doesnot matter much, what matters is traffic, backlinks and "revenue". Is your site good and high in the SERPs and rankings ? Is it getting good traffic? If you are not getting enough revenue from the hard work you do, what will you achieve by getting high pagerank ? Well Id you are aiming for a PR1, then my best suggestion, get the list of networking sites given in the addthis widget and bookmark/submit all your articles in each and every site listed. You will get your result within couple of months
PR is useless...Don't waste your time ! Instead focus on getting good SERP rankings by building good quality links
I think quantily backlinks depends on content and PR of sites innsert backlinks. now google ranking follow content and quantily backlinks