The magic answer is time and hard work
What is the magic answer to get better at chess?
When looking for books or video, make sure they're rating appropriate. You don't want something way too easy or much too difficult. Also be engaged in the learning process. Pause videos or stop reading every few moves and just look at the position on your own. What would you play? Why? Then continue.
Also it's useful to analyze your games with stronger players.
In general the more you read, play, and analyze the better you'll get. And remember more knowledge doesn't necessarily mean more rating. You have to be willing to change the way you play. So seriously and honestly look at your losses. Don't only examine bad moves, but also bad thought processes.

A few generalities that are probably safe to make:
(1) Each person has their own best way of learning. Part of the needed learning process is finding what works best for you.
(2) When you notice that one particular piece of learning material closely addresses one of your concerns, such as explaining why one move you have been making has not worked out, or how to defend against some attack that always succeeds against you, then there is a good match of learning material with your needs, and that will be a good clue about the level of instruction that is good for you, the focus that is good for you, and the type of media that is good for you.
(3) There is no magic. Martin_Stahl's answer is basically correct: Work almost always pays off. Maybe the work will do nothing more than to reveal what *doesn't* work, or what mistakes to avoid, or something more abstract of how to learn or focus or research, but work is as close to magic as you can get, especially if intelligently and wisely focused. The real estate business espouses the wisdom: "Luck is spelled W-O-R-K."

When we study chess we look for general precepts eg Develop pieces in the opening, rooks belong behind passed pawns, knights like blocked positions and a thousand other "rules" - but chess is a game of exceptions and players who understand exception make exceptional players....
In order to understand exceptions we have to analyse. I reckon we can all be a bit lazy with this and rely on our database of "rules" too much. The key to being a good chess player imho is to ANALYSE THE GAME IN FRONT OF US AND GIVE OUR FULL ATTENTION TO IT and the extent to which we can force our minds down the analytic pathways will determine our success.
So much for intellectual effort. Emotionally we can feel confident, nervous, overconfident,impatient, tired (?) etc etc. After a game, I have found it useful to review my emotional state after a critical (bad) move in order to be aware of it for later games. Over confidence has been very common with me.
Hello, I have studied every subject about chess but I have only ended up becoming confused. I wish I REALLY knew how to study chess and what system works.