User data signals
Background. To make sure your website and all site-related activity looks natural, Google collects information about it through all possible means - Google toolbar, Google analytics and all kinds of 3rd party relationships all over the world. In particular, Google is looking to see how long visitors spend on the site, which pages they visit, which links they click, where they go from that site and whether they come back after leaving etc.
By doing this, Google wants to find out if the website is used in a manner that Google deems natural and that it provides information that users find interesting and valuable. Occasionally they even review of websites manually and may either reward or penalise them depending on the results of investigation.Implication. Fill your website with original, entertaining and informative content that your targeted audience is likely to find interesting and useful.
Authority is another factor that strongly affects website SERPs.
Background. Neither Page rank, nor the link juice are any longer that important for ranking. Having lots of links from many internal pages of a website does not improve your rankings much when compared to having just a single link.
Implication. There is no need to acquire multiple links from the same domain.
Diversity of link sources
Background. To rank high it is important to have more links from different independent domains. Independent in this context means belonging to different owners with different registration details and on servers with different free IP addresses.
Implication. Concentrate on expanding diversity of your link sources - try to get links from more different domains, rather than multiple links from the same domains.
Analysis of Link growth rate
Background. If Google notice a sharp change in your link growth rate, they are very likely to attribute it to unnatural activity and are sure to penalise you for this either by imposing a filter on your site or totally banning it from index.
Implication. Grow your link mass steadily. Doesn’t matter at what rate you start building your link mass; choose any rate you feel comfortable with and stick to it during the whole link building campaign.
Analysis of link distribution
Background. Getting all of backlinks to your homepage looks to Search Engines unnatural and your website will never rank high if you have 99% of links pointing to your home page. It tells the SE’s that your site content is not important and that all valuable information (if there is any) is contained on your index page.
Sites that fall into this category, will never acquire high Trustrank and, as a result, have very low chances of ranking high in SERPs, especially on competitive terms.
Implication. Build deep links to various internal pages from various independent sources on different domains. A good number of deep links will help you to build better Authority and, as a result, rank higher in Google.