Google recently changed algorithm, like I pointed out earlier, which helps them to find out the most useful content for a given search query. How they achieved that is another topic altogether. And with a closely guarded algorithm, we can't do anything but guess. Leaving the technicality behind, lets talk about the effect.
Write for the human readers: The first thing to consider is that, according to Google itself, do not write for Google. Do not write even keeping Google in mind. Just write some great content which the human readers will like and your duty is 90% done. Google wants to present to the searcher with the most relevant, most informative and most useful article or webpage and so they will of course place articles displaying those traits at the top.
Think of 'WHY' before writing any content: Nobody likes to read useless information, no matter how well or creatively you have written them. The same is applicable for Google. Google doesn't want to present these pages to the readers as well. So, before you create any online content, have a very clear purpose behind creating the page. Once you have a definite purpose and you know what are you going to share with the world by creating this page, obviously your content will be pithy, useful and relevant. These contents are for sure to get a good ranking in Google.
Socially shared content: This is the latest point which I would include as the last point in this article. In this social age, the more people like your content using Google +1 or Facebook 'Like' and other social media, the better it is in the eyes of Google. Also, if your content is getting shared, referred to in the prominent social media, Google will consider this as a sign of a great content. On a technical note, never miss to have those Facebook, Google+, Twitter buttons on your webpage. Display them prominently so people can actually click on them easily if they like your content.