Here is one link building tip. Use Varied Anchor Text.

Google is getting smarter and smarter. It used to be that if you have a site with all anchor text being "red widget", then you'll rank high on that keyword. Then Google saw that webmasters are putting massive links and keep on using one anchor text.

There is nothing wrong with this but what happens is that webmasters can manipulate the search engine rankings. It would not be a problem if the content of the top sites for "red widgets" are quality content but some sites that ranked well have basically the same content, some less quality content, and some, no content about 'red widgets' at all, just some scraped "red widget" Google search results and an adsense ad.

Google noticed that real high quality sites, the ones that people refer to often as a good resource for a certain topic, has varied anchor text.

Let's say a good "red widget" web page discusses about red widget information, red widget features, red widget prices, red widget benefits. When people see this web page, and they thought, "gee...this looks like a great resource for red widget. My site is about blue widget and some of my visitors might be interested in red widget so I'd better make a link to it."

Now since different people think different way, they may link to the red widget site using varied anchor text such as "red widget benefits", "red widget information", "red widget prices", or even "click here".

Given this information, google used this "natural linking" observation and use this as one of the factors for ranking. Remember, the more natural looking the links are, the better chances it has for landing on the top search engine results.

It is bad to have a link with only 1 anchor text. I have done some experiments on this a few months ago. What I did was just use one anchor text for all my links. The result, it didn't quite make it to the first page. Not until I've added more links using varied anchor text did it went to first page.

Of course some people might argue that the added PR juice coming from these new links did it not the anchor text. However, if you check out with other SEOs, they're also having the same observations. Varied anchor text do help you with your rankings.