One question many artists face when learning art, or anything, is:
Answer is: You don't.
Many great artists I've read about almost always say they're never content with their work. Picasso was still painting when he was past 90 years old, and Henry Miller was still chasing women. That is the beauty of art, it's very elusive. One day you could be blowing people's socks off and the other day you can't even imagine how did you make through the industry with such crappy work.
The problem arises though, when an artist gets obsessed with learning and does nothing. I'm struggling with the problem myself in the quest to become a better artist. It's very confusing. Take this for example: when I'm in a period of studying, halfway through the course I oftentimes get very antsy and want to apply what I'm studying to something. I want to create, cause I believe that is one of my missions in this world. But at times when I am creating, I find myself looking at the work and my mouth would just curl up in distaste. It's not enough for my standards and I barely improved. How do we deal with this dilemma?
My proposal is this: Learning-teaching-doing-cycles.
It is what it sounds like - an alternate cycle between periods of learning, periods of teaching and periods of doing. So for example I suck at drawing hands(which is actually true atleast for now), I would spend a month doing 1000 drawings of hands from copies and my own, really learning it's construction and how it works and then spend some days creating a tutorial about it to cement the principles in my mind and finally a give a month on my personal project and applying what I learned to it.
Some people can actually learn a lot from little amount of study and apply it immediately to their work so this may seem like overkill but I find that I need to do something for a period of time in order for it to "settle" and get hard wired in my memory.
The other kicker here is the teaching part. I believe in giving back to the community, and teaching is one form of how I do it. I love the fact that I can help other people out by doing something that I normally do in the first place - studying things and organizing it into some sort of a tutorial for myself. And as they say "to teach is to learn twice", I'd take up on that offer anytime.
Finally, we get to the "doing" part. The part that will test your mettle. If you think you've already mastered drawing hands, apply it in your personal comic and watch as you get humbled by that upshot of a 3-fingered ogre hand flicking a cigarette on page 15. This is the time you will doubt yourself and the studies you've previously made. You will say to yourself: "I've wasted a whole month making a thousand studies of hands and I can't even draw a chunky ogre hand!". If your find yourself doing this, stop. Remind yourself that this is an ongoing process. Even the greats make mistakes. In the cozy scene for the animation short "Feed the Kitty", Chuck Jones drew hundreds of expressions for Marc Anthony over and over again until he got the one that's just right. He didn't pull out a piece of paper, made a few elegant strokes and presto! - the perfect expression was made. No, he made a lot of mistakes, and he was one of the best animation directors the world has seen. Give yourself permission to make mistakes, don't be sloppy and remember what you've learned, but also don't pull your hair out if you didn't draw the thing right the first time.
In my humble opinon, what follows is a better mindset - You did your best for what time you could spare to learn, helped people with your tutorial and got a little bit better in the process. And in the end, doing the best we can on something we love is all the world and our deeper selves asks of us.