>>120546551/ic/ has good materials and from time to time really great advice. Be careful though, it's pack-full with crabs.
Fundies are your bread and butter. It's good to grind them even when you reach high levels of skills. In any case, it all depends on what you wanna draw.
If you wanna master the figure, this is how I would go about it:
1) Technical exercises - line exercises and drawing the core shapes (sphere, pyramid, cube, cylinder, cone) >Gives you confidence, muscle memory and by knowing how to use shapes, you can build pretty much whatever you want later on.
2) Gesture - capturing the feeling and idea of the figure. >Deceptively simple but requires a lot of millage to master (without good gesture work your poses will looks stiff and unnatural - something I still kind of suffer from) Materials are easy to find on this subject and it doesn't require any anatomical knowledge. You can draw just stick figures and that will do for a while (the goal is to be able to create "mannequins"- gestures combined with the basic shapes and correct proportions to ...shape any figure you wish). Good for warmups too.
3) Anatomical knowledge - Proportions, structure, volume, learning the muscles, which are where, how they interact with each other and how they actually look. (My advice although vague is - simplify, always and divide and conquer /avoid trying try to learn everything at once. It's not only inefficient but you risk of getting overwhelmed which may harm your skill progression/). Point behind anatomical knowledge is obvious.
This is part I
Part II is the other part of drawing/art which it has it's own rules and challenges and you shouldn't tackle in earnest until you've reach some mastery in Part I.
1) Values, Shadow/Light - Understanding how light and shadows work and how they help shape up everything - being good at this will make your works less flat and more 3D.
2) Color knowledge - Color theory, how colors interact, change and affect everything.
