Have a varied anchor text

Target your keywords but make very sure to vary the anchor a lot. Even a few “click here” is good to get.
Come from related pages

This is probably the most important, especially for english web sites. It is commonly believed that links from related pages carries more “weight” (not PR).
Come from different locations on the linking pages.

Don’t have all the backlinks from footers or any other specific place. Have them on the top of the page, inside the body text, navigation, footer etc.
Placed with a gradual natural increase

Don’t place hundreds or thousands of links to a new site the first days … I have tested that and gotten the site banned in Google. You need to gradually place the links and the quantity all relates to how much links the site is usually getting. So if a site usually gets 10 new links per week then don’t place 100 suddenly one day.
Placed from pages with a varied PR value

In my opinion not more than 15-20% of your backlinks to a site should be from PR 5+ pages.
Come from good neighbourhood

Don’t have a majority of your backlinks from adult, pharmacy, and poker/casino sites. Such sites are known to spam and I am pretty sure Google frowns upon them.
Come from different C-class IPs

Google sees this. Have your links coming from total different sites.
Come from both old trusted as well as new sites

It is also good to mix this up.


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