Google's algorithms have changed so much recently, that if you're not careful about how you build links, it's very likely that you're going to end up losing everything - your position in the SERPS, the visitors to your website, and ultimately, your livelihood!
If you haven't got powerful, white hat links from very high authority websites, then you don't stand a chance in today's ultra competitive environment.
The problem is, that these links are very hard to get. That's why Google give them so much weight.
I'm not talking about private blog networks, sponsored posts, guest posting, or any other link building scheme. I'm talking about links from some of the most trusted and respected websites on the planet.