Perhaps try playing games at slower time controls to decrease blunders, and after your blunders decrease only then start playing blitz again. I'm not an expert and neither is my advice, but I'll try my best to help.
I am getting weaker
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One tip I would give is to drop the Sicilian. The Sicilian is way to delicate and the smallest mistake could cost you the game. Play it once you become way stronger, they say you should be at least 2000 to play, but I would say 1500, maybe even 1300. I will be giving more tips later after I analyze some of your games.
Don’t play London either, they say it’s a good beginner opening but I don’t see it. I’m 1500 and I don’t know how to continue after the opening phase. In my opinion you should play e4 and develop your pieces.
You should understand what your opponent wants to do, what they are trying to accomplish with their move. Just get the gist of their idea, you don’t have to dive too deep. For example, your bishop is defending a knight and that knight is under the sight of the queen. If they try to capture your bishop, you can see that they want to capture your bishop so your knight hangs and falls as well.
I am getting weaker and weaker at chess, I really have a passion for chess but I have been playing chess for years but I have gotten no improvement, I'm still in the 500-600 rating range and always was. I used to have coach and used to learn and improve a lot. But now I don't have a coach and I'm getting worse and worse at chess. I am losing many games to the silliest mistakes. If you have any tips to improve independently please tell me, thank very much to those who do. I want to become a chess expert.