Google Rankings Algorithm Changes

Google released several ranking algorithm updates in 2011 that tried to filter low quality websites from the search results.
Scraper websites or websites with low quality content don't get high rankings anymore. Due to these changes in Google's algorithm, some websites saw a traffic drop of 75% or more.
To do: don't try to promote your website with quick-fix solutions. Quality is more important than quantity.

Social signals such as the number of Google +1 clicks, Facebook mentions and tweets now influence the position of your website on Google's result pages.
To do: add social sharing buttons to your website and encourage your website visitors to mention your website on social networks.

Most result pages on Google show much more than a list of 10 web pages. Search results now include images, videos, news, local results, etc.
To do: use a holistic approach to promote your website: optimize the content of your web pages, get good backlinks to your website, offer local services, submit videos about your business to Google to make sure that your website gets listed in all possible places on Google's result page.

Searchers tend to be happier if they get what they want as quickly as possible. Although site speed is only a minor factor in Google's ranking algorithm, it makes sense to optimize the performance of your pages.
To do: make sure that your web pages load as quickly as possible.

Although Google has the biggest market share, Yahoo and Bing now have a combined market share of about 33%. If you're not getting 33% of your traffic from Yahoo/Bing than you should start to optimize some of your pages for Bing.
To do: if you want to get 33% more visitors, optimize some of your pages for Yahoo/Bing.