Link building has always been a hot topic. In the beginning of the web hyperlinks were virtually the only way to get visitors to a site, because search engines were in their infancy. When search engines grew to be the major source of the web traffic, links didn't lose their weight, as search algorithms started to rank sites according to the quantity and quality of their incoming links. And today links become increasingly important with the growing significance of the new Web 2.0 social networks.
Link Popularity Building Strategies
Thus, links rule the Internet. Once a routine task of a webmaster, link building has emerged itself into a full scale industry with millions of dollars in turnover. Ranking algorithms perceive links as a proxy for a human judgment, or a user's positive endorsement of a page. The idea is as follows: a user discovers a page, likes its content, links to the page, and the page gets higher ranking. This is the so-called 'natural way' of acquiring links.
The natural way of acquiring link works is too slow and can be pretty unfair. New pages on big and established websites are far more likely to be discovered by web users, and these pages will get the major part of the new links (like 90%); while new pages on fresh sites will get trinkets. This is a serious defect of the link ranking system which is discussed more in details in my article Popularity Ranking Faults.
Since the natural way of getting links for a new website can take forever, some additional boost is required. There are many strategies of link building able to ensure you some initial ranking and exposure, which are necessary to make the 'natural way' work. Some of these strategies can be very tricky and do more harm than use. So it is critically important to keep in mind the following tips of link building.
Link Building Tips
Be a user when building links. The point is to make your link exchanges look like they are acquired the natural way. Make sure that your links appear in places where search engine expect them to be. This should be pages relevant to your content. Link must be in the page copy or in a sidebar possibly among the other links pointing to pages also relevant to your topic. The anchor text must look naturally - so no keyword stuffing.
Analyze your own motives of linking to the sites you like. What motivates you to cite a web resource? Is it a collection of online tools or handy tutorials? Or may be it is a provoking title? Apply this 'reverse engineering' to your pages, and use unique interesting content to attract links.
Avoid things that can damage your reputation in the eyes of search engines. No link farms, suspicious looking websites or poor quality link exchanges. Forget the reciprocal links - they no longer have any significant weight. Do not participate in three-way or similar linking schemes - these attempts to disguise reciprocal linking are easily to detect. NASA managed to get a man on the Moon with computers less powerful than a GameBoy, so why do you think Google can't discover link triangles with all the computing resources at its disposal?
Buying links. This practice is pretty much discouraged by Google, because it undermines the idea of the proxy for human judgment. So you have to be especially savvy when buying links. Avoid link trading sites or any site publicly announcing that is sells links. Don't mix buying links with paid advertising. You pay for an advertisement on a high traffic page expecting visitors referred by your ad. Buying links has a different purpose - increasing your link popularity.
Do not be obsessed with backlinks. There is an intense focus on link building but not enough focus of content creation. Links must reflect the quality of content. If you think your site has not enough incoming links, you should think about how to improve the quality of content and make it more appealing, not about more link exchanges.
Link penalties. Many people are afraid to get penalized for linking or being linked by fishy websites. If there is a need to put a link to a site which you do not want to be related with, use rel 'nofollow'. Google confirms that this attribute is critical in link analysis, so you should be fine. Links from dubious sources to your site are out of your control and all the major search engines assure that they don't punish people for that. However too many links from such sites (like tens of thousands) can bring an unwanted attention of search engine quality teams. They can ban your site if they found you responsible for boosting your rankings, but you can always submit reinclusion.
To sum up:
Make your linking strategy look natural. Avoid the known patterns of artificial link building and do not obsess with links at the expense of content creation.
Get more useful info on promoting a site in Google at our SEO and Web Marketing Research.