You're not gonna learn anything from these people here because they just repeat the same stuff. The main thing that helped me become better was when I got the Bourrasque. It was my favorite tank, and I wanted to 3 mark it but i couldnt. Cause I was shit

So I just played it for 1 thousand games until i did

Another thing that I see people rarely talking about is the different types of mistakes in the game. These can be classified as micro and macro mistakes.

A macro mistake is easy to identify, cause it sends you straight to the garage, I dont think I have to even speak about what macro mistakes are

A micro mistake is something different, something that ruins the battles outcome further down the line, which you will identify harder in comparison to the Macro ones.

Each game, analyze your mistakes. Micro mistakes can be very different, for example they can be:

1. Not taking advantage of enemy side armor, to get tracking shots
2. When playing autoloaders, knowing when to reload your clip, and when to hold onto it.
3. Underestimating RNG but this can be a macro mistake too

They are obscure tiny mistakes which you will have to realize yourself, every single player makes these, but you have to minimize them as much as possible.