Many people ask the question, how long will it take to become a master if I started studying right now? Unfortunately, I don't know the answer to this question; there are way too many variables to consider. Fortunately, I do have the answer that will lead to the quickest chess improvement: Tactics!
Most games are decided (or should have been decided by) tactics; even the more so for games where one of the opponents are <2400. Studying tactics improves not only your tactical ability but also your calculation, visualization, and even your positional skills. You'll notice as your tactical abilities increase that you can justify your seemingly positional moves with tactics. Click here for examples of tactics justifying positional moves.
Just in case you don't believe me below are tactics that came from my last two rounds of the Leigh Hunt Memorial and a tournament game played by my very first "student"!
Round 6
Round 7
Tactics From An Instructive Game Between Two B-Players
In the above puzzle, can you find the move that Black played that helped win him the full point? Hint: think of a nice defensive resource
In the above puzzle, can you find the move White should have played instead of 37. Nf5?
The entire game:
Conclusion
Tactics are the quickest way to chess improvement. This is because most of our games are decided by a tactic and the mistakes that lead to the tactics.
However, before you throw away all your opening and positional/strategy books, please consider how you can arrive at a position that has tactics in your favor. Once you get to a certain level, your opponents are not going to be nice and just blunder for you (at least not all the time). You need to apply pressure to make them mess up. Some ways to apply pressure are playing a good solid opening, starting a dangerous attack, carrying out a positional plan that leaves with superior pieces or leaves the opponent with a weak pawn structure. So studying areas of chess besides tactics is also beneficial to your chess improvement.
My advice is that you should spend at least 50% of your studying time on tactics. I've seen way too many a student spend hours and hours on memorizing opening lines, only to blunder a knight 2 moves after they are "out of book". The best way to improve at chess is to be well rounded in all areas of the game; I'm just suggesting to concentrate a little bit more on tactics. Hope this helps, good luck with your chess in the future!