Get back links from good sites. Post ur comments in blogs, forums and try to have original content in blogs and also update ur blogs regularly.
I've been wrong before, probably will be again some day, so I don't doubt that I misread the post's intention.
What I meant is that you may see a link to your site on another site but they may have set it up so it doesn't pass any value to your site, just visitors, which is valuable but not in the Google PageRank sort of way. Redirected links trough an interstitial onsite page, links with rel="nofollow", a link on a page with robots="nofollow", a page that is blocked by robots.txt, javascript link, etc. There are many ways to obfuscate a link and just visually seeing it on a page or noticing refererals for it in your logs does not mean that you are getting credit for it. On top of that, it's been mentioned that Google may even remove a sites/pages ability to pass PageRank even though it may still have visible toolbar PageRank.
Yes not that much, but forum links are also considered as an additional backlinks that may add up to PR, but not that much.
Get quality links from quality/old directories which have a strong PR for subpages. If a site is new, I dont think you would start earning natural linking immediately. It will take more time, provided you have useful resources for others. Try to spend few dollars getting quality links from web directory immediately. Some directories also allow free submission but with no guarantee that when or if your site would be added.
The right way to increase your website's PR is to gain more quality incoming links to your site. But before that you have to make your site useful adding more content and resources. After that you can exchange links with high pagerank related websites that definitely will help to increase your website pagerank. But remember PR is only updated once per quarter, so have patient.