There is no shortcut that you can take to improve your rating magically, but there are some proven ways by which you can accelerate this process and improve your chess rating.
You have to study openings, endgames, tactics, strategy, classic games of masters and then practice what you have studied.
Then, good results will follow you like your own shadow!
How to Improve chess rating from 800
The Short Answer: Solve Puzzles and Learn basic Opening Principles
One of the best and most effective ways to improve your rating from 800 is solving lots of tactics.
I believe with just solving tactics and having some basic knowledge of opening principles is enough to take your game to the next milestone.
Over here the most important part is to be consistent in the process of solving tactics and doing it regularly.
Also while doing so it’s important to grasp the various chess patterns you are solving and store them in your subconscious mind.
For Reference regarding the opening principles, you can follow this article.
How to improve chess rating from 1000
The Short Answer: Play Rapid Games and Learn one opening with Black
One of the biggest mistakes players make when they are improving as a chess player is they play lots of Blitz games. This is one of the things which could damage your chess progress and make you stuck around this rating range.
To improve from here you have to replace the blitz games with the rapid time format around 10 Min or 15 Min+ 5 Sec Increment.
Also after the game, you should build a very important quality in yourself to analyze and identify the mistakes you have made or how you could have improved your play. You may learn much more from a game you lose than from a game you win.
You should already be focused on building your opening repertoire and I suggest to at least have one pet opening with Black. And start playing it almost exclusively in all of your games.
This will help you to improve the knowledge regarding the same opening and also the grip of the opening would increase. This will help to make decisions in the openings fast and intuitively.
How to improve chess rating from 1200
The Short Answer: Study Basic Endgame and Learn to open with White
Having a basic understanding of different endgames is a must for the players to improve from this level. This will not only help you to improve as a chess player but also your knowledge regarding the game would improve at a whole new level.
Also studying endgames gives you the confidence to transform the game from winning middle to the won endgame.
To develop yourself as a complete chess player it’s important to have an opening repertoire for White pieces as well. You should know what you should be playing against different set-ups and how to manage the position in the resulting middlegame.
How to improve chess rating from 1400
The Short Answer: Study Classical games and improve your calculation and Visualizations skills
Around this level, you already have knowledge regarding the endgames as well as openings and different types of tactical patterns and themes. Now it’s time to upskill them by looking at how the great players of the past have played chess and learn from their games.
Studying the master’s games of the past not only improves your knowledge regarding the classics but also helps you to understand many different ideas. All the strong players present today know their classics very well.
The calculation is the only way in chess by which we can look at the future in chess and make decisions accordingly and this skill cannot be ignored. Constantly training various tactics and focusing on visualization is a must for players to improve their rating.
How to improve chess rating from 1600
The Short Answer: Have a training Partner and Study positional Concepts
Having someone to work with be your friend or an online buddy is always a blessing in chess. I highly recommend it if you have not already so as to start working with different players.
This will not only motivate each other to pursue new heights in chess but also act as strong support. There are lots of things one can do with the training partner that one cannot do alone.
Since you have already learned the fast-paced game (tactics) it’s time to focus more on the positional game. I recommend studying the games in dept by the players like Tigran Petrosian, Anatoly Karpov, Boris Gelfand.
This will help you to have a strategic balance between your games and make them sounder.
Some Personal Thoughts about Rating
When I look back on my chess journey as a chess player till now (FM) I feel as though the more I was focused on improving my rating (the number aspect) the harder it was for me.
The day I stopped caring about it and instead started to focus on the process of improving my game which ultimately took my game towards the next level and my rating followed me like a shadow and it improved even without me noticing it.
You should treat rating just as a milestone in this whole process of improving as a chess player. This will help you to have the right kind of attitude and maximize your chances to improve your rating.
Being said that let’s look at some of the ways you could improve your rating from the different milestones. Being said that in my career I have seen people being so obsessed by their rating that they forget to enjoy the game of chess.
I believe with this kind of attitude it would be very difficult for one to improve his rating.