Well, if you?re serious about this.
You don?t need to improve your style you need to improve your general drawing; the style can come a little later on. I can only really give you advice on drawing as I don?t do comics myself and so my knowledge is limited on them and storytelling but I can guess what is important.
Draw from life; learn how to draw things in 3d space and how to create the illusion of 3d on paper. Start off simple; draw cubes, bottles and pay just as much attention as to how light and shadow work.
Draw people, lots of people in lots of different poses, preferably from life to but photos can be used, draw from your imagination as well though. Learn human anatomy, you can start out with muscles and skeletal structure but personally I started with proportions and then went into the other stuff, and learn dynamic posing. I don?t know what kind of comics you want to draw but nothing is worse than stiff characters; even if they are just standing you want it to look natural so even drawing people being all boring and just standing around is also important. I mean really, how does a person actually stand, what is happenng?
Perspective and colour theory are important also, start with the very basics of these, drawing from life will help with these two immensely.
Clothes; learn how fabrics behave and how they sit on a person/surface and are affected by gravity.
With comics especially I also imagine composition is key, you need to figure out how each individual panel is going to work and how it is going to work as a group of panels, how the word bubbles are going to fit in, how the layout of the page will look and how the whole thing will flow. What I know nothing about is telling stories using comics and how that should work; you?re going to have to find your own recourses for that. What I do have is plenty of stuff to help you learn to draw if you want them? I have websites, forums and some free online books.
My number one bit of advice; if it frustrates you, defiantly continue with it. Don?t ever not draw something or attempt to hide it if you?re struggling. What I find to be a good example of just that is people quest to hind the hands, it?s really quite funny the lengths some go to so they don?t have to draw them. Don?t be one of these people that cross a characters arms, puts them behind their back or stuffs them in pockets at every opportunity.
Write a lot, write lots of different stories even if a lot of them a quite short, like I said I don?t know how to tell a story outside of a single image myself but I know it take a lot of time and effort of its own. Dialog along I imagine can be quite difficult to get right and make it seem natural. Observation from life will help here to.
Typography; It?s not just what you are writing the text itself is important.
TL;DR, Draw everything, draw from life draw from your imagination and take an interest in the world and how things actually work and look. Look at anatomy, perspective, composition and composition in comics, colour theory. Write a lot, pay attention to how conversations work in life. Start with the basics and work from there, move about and try to take in as much as you can. And of course, practice, lots of it.
Two years? It?s plenty of time to see some improvement.