1. Join forums, forums can achieve links to your website. In most forums you are allowed to have a signature, put the link of your website on your signature. If the forum is somewhat related to your website.
You will be advertising for your website (bringing in targeted traffic) ,You will also be building your websites presence.
2. Update your website every day by adding more and more unique content. If you provide good information to your visitor then the visitor will come again for sure.
3. Provide inside linking to your website. For example you can provide a link of your previous and next articles on an article/blog page. Or you can provide a list of related articles so visitor can remains a long time on your website
4. And the most important tips. Trade your link with other web owners. Put their link on your website and they will put your link in them. This is cheap and very fast way to improve your visibility in search engines.
5. Submit to directories and sit relax. Start one by one and submit your link in all web directories. If you can, try to give a link back (reciprocal link on your page) to free directories, some directories does not need it, but if you provide them, their owners will look for your approval first.
6. Social Bookmarks – Tag your sites in social networking, bookmarking sites like Digg, twitter, StumbleUpon and Technorati. Every time you have a tag out there is one more inbound link. Links to your site will improve your rating,
7. Trading links – Several of your friends might have their own websites or blogs. Ask them to post a link to their site and they post a link to your site.
8. Keywords / Metatags – Every page has a unique page description and a unique set of key words. While many pages use the same key word, no two pages have the same set. The key word list contains a long list of words related to information provided on our site. We also make a point to use the keywords in our post. This increases our keywords density. According to Google, the greater your keyword density, the more relevant you are.
9. Getting a link on a trusted domain’s resource page like a university or government site.
10. Buy an old or expired domain, or buy an old domain network that has PR, and transfer PR in by way of links or 301s.
In the end, you should not be thinking about improving your Pagerank. Pagerank is an after effect.
I think a lot of it is to do with click / crawl depth. For instance, forums don’t pass a lot of Pagerank these days compared to what they used to, but maybe that’s because they’re just bigger. Most low quality directories don’t seem to pass a lot of PR. Social media sites seem to suffer the same problems as forums. I don’t think blog comments pass a lot of PR either.
The fact is nobody knows how it works these days, it’s probably far removed from the original pagerank paper, and while it may still be a defining entry level requirement for competitive SERPS, it’s not an important element at all when it comes to ranking pages that are already in the SERPS – there are other, much more important influences.