Before I say anything else, I'll say this -- hands on experience. Writing code. I have Visual Studio with the Vim plugin on my Windows machine, so the only limit is my time and energy.
I have always used books. I like books. But I have enough darn books, and besides that I am just sort of sniffing around to see what the language is like. I am not serious about any real projects, and I am not getting paid to do work in C#. So I am going to see how far I can get with online resources.
Of some importance is the fact that C# is a moving target. It has been steadily changing with each version. I am now working with version 11 of the language with .NET 7.0. I have no idea how much stability the language has and whether I will be tripping over out of date information.
These resources look good:
Tom's Computer Info / [email protected]