That’s awesome that you want to go in this direction! We were 15 when we started to get really serious about art, because up until then, our art , well, let’s say we aren’t showing those drawings anytime soon . ;) So you’re young-er, and you don’t need to be comparing yourself to other artists! Actually, we all don’t need to compare ourselves to other artists! It really can wear on you after a while.
As for self-improvement, we’d encourage you to take classes if you can. If it’s available to you, that is. Our learning methods were quite straightforward in regards to being self-taught. Art of Books, looking at other artists’ blogs, and just drawing everyday (even during school if you can, haha) - take any opportune moment to study the works of people you admire. We never suggest down right copying someone’s work, but look for the aesthetics you find appealing and apply that in your work. Draw what you would like to see in your work, (even if it doesn’t come out right the first 1000 times) , and even branch out and try some other method too. We have found out that once you have kind of “mastered” one thing, even your inspirations branch out! For instance , we never really liked looking at pen and ink drawings, or didn’t find them to be as inspirational up until we started working with people at work who use it all the time! Mostly because of intimidation of never using the medium caused us to not find those mediums as enjoyable to look at. But now that we’ve dabbled in ink and watercolor , we enjoy that work a lot more now because we aren’t as “afraid” of using them. It’s like unlocking certain levels in a video game or something. Something just clicks. And that’s the fun part about being an artist. You’re always constantly growing, learning, and appreciating new things! Which all of this babbling is meant to say, at this point in your artistic journey , just have fun learning and just drawing for the enjoyment. We all tend to get wrapped up in one upping some other person or putting ourselves down, that the joy of creating art with an open and free mind becomes more of a chore. That’s just our opinion anyway. Good luck to you and God bless! Only with time and practice, will you reach a point where you can say , “I’ve got it!”. And when you reach that one point, you can move on to another! :)