EDIT ( edited on January 8th, 2014 ):
Some of the other excellent answers pointed out a flaw in mine-I have failed to mention the importance of analyzing ones own games. This is corrected bellow, for the sake of completeness. I apologize to the OP and others who found my post useful.
First off, let me say Happy New Year and Marry Christmas to you!
Second, you will have to invest quite some work to be really good, but I believe it is doable based on the information about your current skill you have provided.
Based on the information you provided I think that you can help me with this and I hope that we can successfully solve your problem.In order to suggest you resources for your improvement I need to get to know you as a chess player. I need to know what pace of play you like, what type of positions you prefer and so on*, but you did not provide me that information so I will cover both options.
So far I have concluded that you are experienced enough to learn successfully from books and tutorials so I will tend to recommend those resources to help you self improve.
Rule #1 that drastically improves players strength:
Know your openings!
You really have to know your openings well, so you do not:
1. Fall for cheap traps
2. Get horrible position which you will hopelessly defend for 50 moves, only to resign later.
If you like fast paced games with lots of sharp, tactical play I could recommend you Sicilian defense against
1.e4, and King's Indian defense against everything else ( King's Indian defense will reduce your time required to learn the openings, as it is very flexible ).
If you are slow paced, positionally oriented player I recommend you French defense and Queen's gambit.
Just search for Staring Out series on Amazon and read those first.
Rule #2 that drastically improves players strength:
Know how to play the middle game that arises from your openings!
To learn how to play the middle games from those openings here is a masterpiece:
Andrew Soltis-Pawn Structure Chess (1995)
A must have-period! This alone can improve your strength by 50%!
Rule #3 that drastically improves players strength:
You must know how to play endgames!
You need to know basic principles, at least, or else you will squander all the advantage you have built in your middle game.
End games are tough to master, and you will need lots of books. I can not recommend one made for beginners at this moment.
You can try with Mastering Endgame Strategy ( Johan Hellsten ).
Rule #4 that drastically improves players strength:
You must be able to exploit tactics in the game!
We have all "been there": You have a "won" game, yet you lose it because your opponent had "lucky move". Or you just got destroyed from the sacrifice you didn't expect.
There are lots of books on this topic, and I will recommend Starting Out-Chess Tactics and Checkmates.
Rule #5 that drastically improves players strength:
You need to know basics of the "positional play"!
Sometimes you will play openings that require from you to "deaden" the position, or your opponent will do it, and without this knowledge you will end up in a "boring game", you will lose focus and your opponent will easily "pick you off". Also, the problem with these openings is that raw calculation does NOT help you to find a plan.
You can calculate until you die, but you will not find a plan-you will need the knowledge of the positional themes to get you by.
Try with Mastering Chess Strategy ( Johan Hellsten ).
Rule #6 that drastically improves players strength:
Analyze your own games! I can not believe that I have forgotten about this one! This is the most important part.
This is the pattern that I use:
- Write down the game you have played;
- Compare the opening you played with the moves in the book about that opening ( here Starting Out series come in very handy );
- Evaluate the soundness of your middle game plan by consulting the Soltis' book, discover all the tactics that was in the position ( computer is great for that ) and consult computer/stronger player/books to see how you would correct both your mistakes and opponents, and most importantly try to pinpoint the game deciding moment in the game;
- Evaluate the endgame that arose-is it won/drawn/lost?
- Evaluate the time you spend in correlation with the position's difficulty-do you get overly excited when things get tough/you are winning so you waste too much thinking time? Or are you too impulsive so you make moves without thinking?
As others have pointed out, your main goal is to play and not to get too distracted with the books I have recommended. Those books are easy for reading, and will teach you the general ideas + give you the least amount of concrete variations so you can get by in your game. My apologies for omitting this advice, I have forgotten about it, but without it everything else is really useless.
Find books from Starting Out series for openings you wish to play. Get the book on middle games that arise from those openings-the one I have recommended is excellent. Learn chess basics-tactics, positional play, endgames. For that, I can recommend the book I have used, but here is a problem:
The book is not written on English and you will have to find the translated version.
The book was written by Vladimir Vukovic, and is called Uvod u sah or Introduction to chess when translated to English. If you get that consider your problems regarding endgame, tactics and positional play solved. If you fail to find this book, try with the books I have listed above ( I have edited my post to provide you a book for each of the rules stated above ). I haven't read them, but I have a good feeling they can help-based on the critics I have read on Amazon.
I would start with opening books and middle games ( Soltis' book recommended above ), and then improve my tactics, then positional play and only then end games.
This will be a long journey for you, but definitely an enjoyable one.
If you ever need any help, leave a comment and I will respond as soon as possible.
Best of luck, call if help required!