I was doing some link building yesterday and a question popped into my mind. let's say I submit an article with my website link to an article directory with a PR 5. Now this website in PR 5 but the page created with my article is probably PR 0. Now depending on the popularity and interaction on this article, it may go up to PR 1 - 4 or it may not and stay at PR 0. So in case it doesn't, will this back link be any useful to me from an SEO point of view? Coz the way I look at it is, if this ink is not useful then I should stop wasting my time and try to get backlinks from homepages or blogroll etc. This brings us back to the same old issue of buying links
Its not only PR which matters. Try to learn more about "Page Authority", and its influence on rankings. Yes, the PR of the page in question might change or not, Still, an old link has its own importance. Also, don't focus on any single technique, like article or directory submission, and try to discover new ways.
I think backlink is an effective way to improve your site ranking, and you should continue to create it. Never be anxious to short term feedback.
diverse link building is definitely the way to go ... regardless of the homepage pr some of that will always filter down to the page you create your link/article on - yes this can be increase by adding to its 'popularity' as seen by google e.g. maybe have some links going to it??
Forget about PageRank, you are chasing an ever-moving target. For instance, if you get a backlink from a PR9 webpage and you are the only link on that webpage, then all it's link juice will flow to you. The next day, spammers may get hold of this page's URL and this results in the webpage now having (say) 10,000 outgoing links. Your backlink now only attracts one ten thousandth of the link juice. In general, certainly it is better to have a backlink from a higher PR webpage than a lower PR one. However, the important thing is for your backlinks to build naturally. The best way to do this is to produce interesting, informative, entertaining and unique content. If you are tempted to buy backlinks then, if Google discovers you are doing so, you are very likely just wasting your money. At best, Google will simply ignore all bought backlinks, at worst it will penalise your website.