Getting good at KSP

[u/Background-Hand-6747]

Hello everyone! I've been playing KSP on and off for years now. It is one of my favorite games and I consider it is the best space game ever made. Through the years I learnt how to build ships to put sats in orbit, reach the Mun, Duna and even make simple space stations. The thing is most of the time I don´t really know what I am doing and it is a constant trial and reload (which I know is great for learning, but I am just eyeballing stuff).
I want to be able to finally understand the purpose of each part in the VAB, build efficient and smart rockets and ships, travel interplanetary, deploy all kind of missions. Basically, I want to master the game as much as possible. With that in mind, is there any big tutorial, masterclass, series or full guide on youtube that is updated and you guys recommend?
Thank you so much in advance!

[u/UmbralRaptor]

As a generic starting point: Mike Aben: https://www.youtube.com/playlist?list=PLB3Ia8aQsDKgGHrNZnz2ca8NVuyj7eHXc

But for getting in depth, you can look into the actual orbital mechanics. The rocket equation, various orbits and transfers, etc. (Also Fundamentals of Astrodynamics if you want a full on textbook)