One thing that's been sinking in as my life as an artist continues is that there is no replacement for experience. There's so much that can only be learned by putting in the hours with a pencil or brush in your hand. This is the physical side of art. Compared to, say, gymnastics or boxing, painting seems like it's not very physical, but really we can't avoid the fact the we must interact with something in the physical world to get our art created. Even someday when we can paint on the computer with our minds, there will be a level of experience needed to get that thing out there to do what I want.
And so we need to learn how hard to press, or how to sweep our arm, or how much of this paint to mix into that paint, or how this brush loaded with this paint will make marks on this canvas. The only way to get this kind of understanding is by doing it as many times as we can, and paying attention while we do it. Being humans, we can't pay attention constantly, but the extent to which we can will speed our learning. But the important thing is to get the hours in. It's popular these days to say it takes 10,000 hours to really master a skill. The saying is becoming a bit hackneyed in some circles, but unfortunately it's true. While it's ultimately better to do it with attention, we can't always force ourselves to pay attention. So, we need to give ourselves as many chances as possible to be able to do it with attention.
When I was a teenager, I spent an awful lot of time copying and regurgitating comic book drawings. I would basically memorize every line that an artist made with very little understanding of why he made it. Then I would dutifully recreate either the exact image or some very slight variation of it. For a time when I was older I considered this approach to be a waste of time- just rote copying with very little comprehension. In one sense, I was right in that this kind of learning is less efficient than others. But lately I've come to appreciate how valuable all that rote copying really was long term. It improved my dexterity, gave me something objective to work towards, and most of all when later I finally learned why the artists put lines here or there, I was able to execute that understanding almost immediately without waiting for my hands to catch up with my head.
While I think there are far better ways of learning than rote copying, there's still something valuable there: the fact that you cannot make up hours of experience. You only get so many in your life. Intellectual knowledge and comprehension comes fairly cheap by comparison. If you have the prerequisite knowledge, one read-through of the right text and you might have it instantly. But to get your hand to move just so- you can't get that for free.
So even if you're not sure what you should be doing, or what the right way is, or what's "correct", get out there and get working anyway. All that understanding can come later, but you're wasting hours worrying about it now.