I'm stuck at 1100-1200 rating. What should I do?

As I wrote in the topic, I have no idea what to do. I do puzzles every day, I know tactical motives and I have a debiut repertoire for white and black. How should I exercise? Sorry for my English it is not my first language.

Study each phase of the game individually and systematically. Not only study openings ( дебюты), but also middle games and end game lessons.

@1
Do not study openings, it is useless.
Analyse your lost games so as to learn from your mistakes.

Hi! You should work on your weaknesses so you should try to discover them first. I' m a Chess.com Coach and can give you some customized advice in a free trial coaching session. Please check my profile and contact me for details.

Regards!

https://www.chess.com/forum/view/for-beginners/the-evergreen-question-from-beginners-how-can-i-get-better

Focus not only on tactics but also on positional systems that will help you pry open the opponent's position. It's like opening a safe and you need a few winning combinations. Studying master games is a good way to get there. Try to emulate similar maneuvers and even though you will fail 99% of times at the start and go down in elo, at some point you start to grasp the meaning and be more successful.
This is actually how Magnus got so far - lucky shots and a good dose of cheerful optimism - and in the end your playing strength improves not incrementally but categorically. It's like bungee jumping instead of learning the trampoline. Cliff dive instead of high dive, etc.

Studying openings is not useless but it if you compare how much would you improve more with studying something else instead of openings it can be considered useless. I was 900 year ago and now I am 1500 rating here. And I am 42 years old, so thinking got slower... I never studied openings to achieve that improvement... I read 2-3 books, complete guide here and that was it... For example, I read a book "logical chess move by move" in which a lot of openings were queens gambit so I learned that, for white and for black, it suit my style... I learned 3-4 moves of caro-kann for black if e4... And when I analyze my games my openings are the best part of my game, just by keeping some guidelines I learned from those books...

When I was stuck around 1200 almost a year ago I read book of Ivan Chernev "Logical chess: Move by Move" and it increased my rating to around 1400... Before that I completed all the guides here on on chess.com (guides). IF you will not pay for guides here I suggest first book to read: "Play winning chess" by Seirawan and Silman... So, read that book, and play games... That book you can read fast but try to implement all of it in your games... So, first that book and play like 200-300 games trying to follow what you learned there...

Logical chess - move by move, I needed like 2-3 months to read it and implement most of the things in my games... From that book I learned Queens Gambit as white pretty good and I have nice rates with that opening.

Now I am reading "chess: the art of logical thinking" which is also great book but do not read it before logical chess as it is a bit more complex... Until you reach 1350+...

It is important not just to read it. I have a friend with rating of around 900 and he read "logical chess" in 10 days and didn't improve anything. So you can't just read it... You need slowly to try to implement one by one thing in your games...

Also, for endings, good book is "silmans complete endgame course"... it is written so you easy learn only what is needed for your rank. For example, no need to learn bishop-knight mate when it is not important for our rating... I even didn't know opposition rule until rating 1500. Lost a lot of King vs King+Pawn games...

Play through hundreds of instructive games on a real board, preferably at a slow pace. This is a very important exercise, but people don't do it, because it doesn't fit clearly into any category, like Opening/Middlegame/Endgame/Tactics. It is a basic pattern learning, including every stage of the game.  

How long have you been training for? You need to spend a lot of time on chess, not just playing games. Try slower time controls, they give you time to think. Maybe read some chess books on some of the openings you play, learn a new one, or maybe look into the ones that annoy you the most. Maybe get a coach and see how you do with them. Analyze all your games, and when you blunder, try finding the correct move without using an engine (if you cannot find it, then check to see what it is.). 

Polish Translation (I understand it a little as I'm from Ukraine, but it's mostly translated):

Jak długo trenujesz? Trzeba poświęcić dużo czasu na szachy, nie tylko grając w gry. Wypróbuj wolniejsze sterowanie czasem, dadzą ci czas do namysłu. Może przeczytaj kilka książek o szachach o niektórych debiutach, w które grasz, naucz się nowego, a może zajrzyj do tych, które najbardziej cię denerwują. Może zdobądź trenera i zobacz, jak sobie z nimi poradzisz. Przeanalizuj wszystkie swoje partie, a kiedy popełnisz błąd, spróbuj znaleźć właściwy ruch bez użycia silnika (jeśli nie możesz go znaleźć, sprawdź, co to jest.).

The problem of stagnation and getting stuck with your progress is very common for chess players. There are more in-details solutions to that of course... but I just have 1 advice for you --> Sometimes training stops being effective, because you are used to it. You are doing the same things every time (e.g. puzzles + playing on the internet) and after some time it's no longer any challange for your brain. For the training to be effective you need sometimes to cross the border of your comfort and challange your brain. So my advice is very simple --> Change your chess training, not even necessarely train harder (although it would be nice), but simply change it from time to time. If you've been doing puzzles + playing only --> Now you can try for example starting a chess book to learn new strategy concepts or put more time to analyze your games.

Study watch videos on you tube gothamchess is good. Hikaru is good. Play alot of games and experiment...thats whats beautiful about chess.com