Most effective way to achieve a 2000+ rating in one year, starting as a 1600? I currently play at around a 1600 level, and have stagnated in terms of rating improvements for quite some time. 

I have always played chess recreationally, occasionally doing tactics puzzles here and there, but I've never done any professional studying.

I was wondering what the most effective way of improving my rating to 2000+ would be.  If there are links to scientific research on the topic, I would appreciate it.  Book recommendations would also be great.   I'm mostly looking for a discussion about what exercises maximize your return on rating-- opening, tactics, positional understanding, end games, analyzing grand-master games, analyzing your own games, etc.
Gaining 400 points in a single year is not a reasonable goal for an adult playing at 1600. To do this, you will need to be +25 against your peers, where a peer is someone with the rating you have at the time the game is played.

That being said, if you're going to try it, the first step is to get an instructor. Your instructor will be able to identify the weakest parts of your game and help you shore those up.  Since you want to end up at 2000, I'd recommend an instructor rated no less than 2200.

The maximum return will likely be on tactics.  You'll need to be decent at two openings as white and two as black.  Know the philosophy behind the openings - don't just memorize the moves.