Links are "the single biggest factor in determining which sites are indexed by Google”
Inbound links, links to your site, are most important of all. The more sites that link to you, the more popular you are. The more popular you are, the higher your PageRank will be. Attempt to get as many, quality inbound links as possible.
Some links are better than others, for example:
Incestuous links can lower your PageRank, These include links from sites owned by the same company or hosted on the same server. Also, links to pages that include links straight back. Try to avoid this type of link relationship. Aim to make your content useful, quality sites will link to you.
For every key phrase, there is almost always an authority directory on the subject. Find them and submit your site, adhering to their guidelines.
Try to get a listing on the Open Directory Project. This provides content for Google, AOL, Ask, Lycos and many more search engines. It’s free, but your site must be useful and approved before it will get accepted.
If you are a business, submit your details to Google local. This will automatically list all businesses registered with yell.com, but submitting directly through Google will allow additional information to be included.
Finally, if you can afford it, submit your site to paid directories like Looksmart and Yahoo. These are costly but can achieve results.
Provide useful links for your visitors by linking your content to relevant sites. Although not as important as inbound links, these do add weight to your ranking.
Don’t link to too many sites, and don’t link just because they ask. Vet every site for relevance and aim for high ranking sites.
Clear, simple navigation is essential for both visitors and search engines to explore your site. Every page must be linked together logically, and available within about three clicks of the home page.
Links within content are also very important. Both visitors and search engines use these links to read surrounding pages and discover the relevance and context of a page.
With lots of internal linking, it can be easy for a user to get lost.
Using a visited link colour will improve user experience by showing the pages already visited.
It is important that the link titles of links to your site contain the key phrase for the page. Ensure that you supply the correct code to linking sites, for example:
<a href="http://featurecreep.com”>
Key phrase here
</a>
Make links contextual and avoid using “click here”, the URL or a domain as the link title.