Though it can be difficult to determine google ranking factors there are several tried and true things to keep an eye on. Often these rules or guidelines are simple and may even fall under "common sense". Here are a few for you to keep in mind.
Does this site provide useful information for the topic it's ranking for? Or is it a lot of garbage filler text, links and ads? Google has made major changes recently to rate the quality and relevancy of websites in order to provide higher quality results to it's users. Always create your website, content strategy and tactics around providing value for your site visitors and prospects.
As the social landscape has continued to grow and dominate how people interact online Google and other search engines are factoring things like likes, followers, retweets, friends, shares and views more and more into how they rank a site. You should actively work to grow your social network and be active on the most popular social sites.
Things like CTR (click through rate), bounce rate, time on site and other metrics tell Google how useful your site actually is. This comes back to making your site useful and relevant. If you do that then people will spend time on the site and look around.
Google looks at how easily your site can be read and how easy it is to find.
Google will look at your code, meta tags, alt tags, H1-H5 and more, in order to determine - in addition to what the content tells them - what your site is about. Make sure you take advantage of these elements but don't abuse them.
At the end of the day you should really focusing on making a great site that is easy to use and contains content that your users want to see and want to share. This can be in the form of articles, reports, pictures, videos, infographics and any other content that can be shared online.