The tutorials in the documentation are supposed to be quite good:
I haven’t tried them myself though.
I learned Godot by trying to make simple games and looking up any problems I ran into. For me this worked out fine (I think 
) but it can lead to some bad practices and you probably won’t finish any projects any time soon with this approach.
For concrete questions (like how signals work, best practices, etc.) ask this forum 
or search for existing answers on the internet. The Godot documentation is also very useful once you get used to it