I learned a lot of this stuff ~15 years ago from reading a book called Reversing: Secrets of Reverse Engineering by Eldad Eilam. The book is old but amazing. It takes you through a whole bunch of techniques and practical exercises. State of the art tooling has changed a bit since then, but the x86 ISA & assembly more generally hasn't changed much at all.

One of my biggest takeaways was learning about "crackmes" - which are small challenge binaries designed to be reverse engineered in order to learn the craft. They're kinda like practice locks in the lockpicking community. The book comes with a bunch on a CD-ROM from memory - but there's plenty more online if you go looking. Actually doing exercises like this is the way to learn.

You don't start trying to reverse engineer COD. You build up to it.