How to get better in chess for 1300 player?

I am an 1300 rated player (rapid) and I did hit a wall here. I can't get over the 1300 rating so I guess I have to learn something here and I have no idea where to start.

I did study the caro-kann and the London system for openings and I play them well but nothing else yet. I am thinking maybe I have to learn a new opening for black against d4 but I don't know what Should I do other than that. Any advices?
I didn't study any chess book before or any thing about middle games or endgames and I don't know where to start.

i think just being more mindful not rushing and always asking yourself how you can make the most threats. For black you should play the berlin, thats my advice. The rest is pretty subjective, you just have to learn to out maneuver your opponent and make more threats, so maybe getting better at puzzles will help?

you can do endgame drills on here if you feel like to need better endgame skills, you can also play against the computer in any position you want, that helped me learn bishop and knight checkmate, its good for endgames

To most of my students, I give this advice (and it's almost all they need):

The biggest reason people struggle in lower-level chess is because of blunders. They make them in almost every game.

A mistake can instantly put you in a bad position, no matter how well you played earlier: if you had great opening knowledge, great positional skills, great endgame skills, whatever; a single mistake can change everything (you lose a piece or get checkmated).

So, how do you avoid blunders? Follow these two simple steps:

1. After your opponent moves, think if it's dangerous. Ask yourself, “What’s his idea?”
2. Before you make your move, think if it's safe. Ask yourself, “What attacking replies can he play?”

If you feel like getting to levels like 1600, 1800, or 2000 in chess is super hard, let's look at it in a different way. Those players you're facing make blunders in nearly every game they play. Beating them isn't so tough if you stop making big mistakes and start using their slip-ups to your advantage.

Again, it does not require you to become a chess nerd or spend all your time on chess. Just doing this one thing can boost your rating by a few hundred points right away.

Lastly, while avoiding blunders is crucial, I also share a few basic principles with my students. These principles help them figure out what to do in each part of the game - the opening, the middlegame, and the endgame. Understanding these simple principles is like having a map for your moves. When you use this knowledge along with being careful about blunders, you're not just getting better at defending. You're also learning a well-rounded approach to chess. Keep in mind, chess is not just about not making mistakes; it's about making smart and planned moves to outsmart your opponent.

I don't think you can learn a new opening and pass your plateu. It takes more than that.

You need accumulation of knowledge and new habbits (maybe losing some old ones) for the next level.

But one thing is certain for sure, your accuracy should pass like 70-75 as a new normal, so you have to stop blundering.

higher rated players don't blunder, they make mistakes.. in more upper levels they only make strategic inaccuracies.

focus on how you make blunders and ways of getting rid of them

@1

"I am an 1300 rated player (rapid) and I did hit a wall"
++ Always check your intended move is no blunder before you play it. Analyse your lost games.

"I have to learn something" ++ Identify and cure your mistakes.

"caro-kann and the London system for openings and I play them well" ++ doubt that

"opening for black against d4"
++ Play Slav Defence 1 d4 d5 2 c4 c6. It goes well with Caro-Kann and London Opening.

"middle games or endgames and I don't know where to start" ++ Start with endgames. First 3 men, then 4 men, then 5 men, then 6 men, then 7 men. Especially rook endings as these occur most.