WarnerC3 said:
Well, it is a rather objective said, like what's fundamentals?

Fundamentals are actually something that never-ending, fundamentals don't stand for easy ,too.
You can even spend lifetime on fundamentals.

So you should find out what you're lacking at this moment
Like coloring, or shaping out the figure etc

Art is about ''observing, performing'' (observation, Performance)
The former means how detail you can look at something,
the latter means how detail you can perform it onto another media (drawing on papers or PC)

Most of the time people try to draw when their hands have no muscle memories

But drawing is relying on your skills , which have to be trained in order to obtain such skills

I suggest Proko courses only, his lessons are interesting, unlike New masters academy , CGMA, whatever i have seen so far

But Proko courses are the easiest to digest for the informations

Go for it :)

Manga doesn't really rely on traditional basics like materials , you can just grab a mechanic pencil and sketch the shapes

And the shapes, by far they're the most important to create an appropriate (or best output) face proportions.

Because it is like the skull ! A skull constructs your face proportion, I definitely recommend people to grab a book of skull studies

If you want to ignore the anatomy that's fine, and not even problematic , if you're only drawing manga

but when you want to draw the detail of the body, anatomy is needed, undoubtedly.