A well-established, reasonably popular blog that has put some effort into publicity and link building might end up with a PR3 or PR4 homepage, but for anything beyond that, a long-term, focused campaign usually has to be mounted.
The greater your PageRank is, the better, but why? It's because PR is a simplified version of the measure Google uses to decide how much authority a website has, and hence how highly it should rank for relevant search terms. The greater your PR, the more chance you have of getting a good stream of organic traffic through search engines.
How can I see my site's PR?
There are plenty of free toolbars that will let you see any site's PR. It doesn't have to be your own.
What increases PR?
Good quality inbound links will improve your site's PageRank. That means links from other blogs (try guest posting), from high quality directories, informational sites, and from forums.
Links come in two varieties- nofollow and dofollow. Most links on ordinary sites are dofollow, which means Google takes them into account when calculating PR values, but some sites choose to make links nofollow, or ignored by search engines, in order to prevent spam or to help direct their link power carefully. Links placed in forum comments are often nofollow, as are links from Facebook and WikiPedia. These links may count in other ways, but if you're looking to increase PR it's best to stick with dofollow links.
The bigger and more trusted the website, the more a link from it is worth. The most valuable link most small to medium sized sites can hope to get is from the human-edited directory at dmoz.org, but they are quite picky. Your blog would have to be a good information resource to make the cut.
Note: DMoz has lost the trust that Google used to give to it in 2003-2004. Now, Google treats Dmoz the same as it would treat any other website with the same link profile. Since Dmoz has such an excellent link profile, a link is still useful.
What doesn't increase PR?
If you wouldn't use a directory to find something yourself, listing your site on it probably won't help you. 'Link farms'- sites that are nothing more than pages and pages of links- will not help you, and may in fact do your site serious harm.
Never trust anyone who offers to sell you thousands of links. The major search engines are pretty good at spotting link fraud and being involved with it can get your site blacklisted off the rankings completely. Simply exchanging links with another site is of limited value. A one-way backlink is much better if you can get it.
Why isn't my PR going up?
If you've been putting a lot of work into linkbuilding but your PR is still zero, don't worry. Publicly visible PageRank values are only updated every few months, and the next time this happens you might see a dramatic jump. You can't see it, but the version of PR used to generate the rankings on search engine results pages is updated constantly so linkbuilding efforts will help your rankings almost immediately.
Note:Google has repeatedly stressed that PageRank is not the only factor involved in Google's algorithm. There are more than 200 factors that Google considers while ranking web pages.
This is a post by Jess Spate.