@Kaspar0vRegen10 said
> I'm a beginner player who started not too long ago.
> How can I improve quickly so I can become a 'National Master' eventually?
You will never become a Master, until you Master Endgame. First things first. -:]
"... On the one hand, your play needs to be purposeful much of the time; the ability to navigate through many different types of positions needs to be yours; your ability to calculate variations and find candidate moves needs to be present in at least an embryonic stage. On the other hand, it will be heart-warming and perhaps inspiring to realize that you do not need to give up blunders or misconceptions or a poor memory or sloppy calculating habits; that you do not need to know all the latest opening variations, or even know what they are called. You do not have to memorize hundreds of endgame positions or instantly recognize the proper procedure in a variety of pawn structures.
[To play at a master level consistently] is not an easy task, to be sure ..., but it is a possible one. ..." - Reaching the Top?! by NM Peter Kurzdorfer (2015)
https://web.archive.org/web/20220625175407/https://www.jeremysilman.com/book-review/reaching-the-top/
"... This book is the first volume in a series of manuals designed for players who are building the foundations of their chess knowledge. The reader will receive the necessary basic knowledge in six areas of the game - tactics, positional play, strategy, the calculation of variations, the opening and the endgame. ... To make the book entertaining and varied, I have mixed up these different areas, ..." - GM Artur Yusupov
https://www.qualitychess.co.uk/ebooks/Revision&Exam1-excerpt.pdf
"... the situations in which trainers work vary enormously. ... Some trainers work with large groups of students and others individually; with average low-category players or with bright and highly talented potential stars. ...
That is why I am skeptical about any attempt to introduce a rigid methodology, rigid rules telling us what to do and how and in what order to do this or that. ..." - IM Mark Dvoretsky (~2003)
“... I consider the approach towards the study of the endgame must be multi-staged and always keep the same pace as the player’s overall playing level. ...
In the first stage, it is enough to master the basic checkmates, King + Pawn vs. King endings, and to know which main material relations are winning or not; in addition a few exceptional and frequent situations, such as the Bishop + Wrong Rook’s Pawn ending, etc.
A second step in this first stage would involve the Philidor and Lucena Positions in Rook + Pawn vs. Rook endings, as well as some more ideas in pawn endings and opposite-coloured bishop endings. In this book, this would amount to Chapter 1 and Endings 41, 42, 44, 45, 46, 65, 79, 80, 82, 86, 89, 90, 91 and 92.
... and actually that is enough until the moment one reaches, say, a FIDE rating of around 1900-2000. Beyond that point, greater endgame skill is a must. At this stage, problems usually arise, but the upside is that this extension of a player's endgame skill will usually be enough at least until he becomes an International Master with a rating of around 2400. ...
At this stage (2000 FIDE) we should move to the second phase and then the first thing to do is to acquire an exact knowledge of some theoretical endings. ...” - 100 Endgames You Must Know by GM Jesús de la Villa (2008)
https://www.newinchess.com/media/wysiwyg/product_pdf/9026.pdf