I'm guessing some people here will want to be PC and say don't worry about it, just do something great and they will come...I its better to do something great and also have some effective PR/social strategies in place. It is possible to game the algorithms, this could be done on a spectrum from light to aggressive tactics. Where you want to be on that spectrum you need to decide.
A simple and mostly ethical approach is to study the viral sites, see which posts take off with massive sharing, and think about how to structure an article/story in a similar way. Even the experts never know exactly what will take off, but they study it scientifically to give themselves the best chances of success. Your post will need some momentum especially in the beginning, it doesn't hurt to think about ways to try and give it a head start.