There is an old observation in the writing world, based on no science at all. It is often said that you don't start to become a truly good writer until you have written at least one million words. And they don't mean just any words either, but words into which you have put specific, concerted effort on behalf of a future audience. Articles and stories, not to-do lists. One million words.
It's a lot of words. Not as many as you might think, but a lot. And it takes a while for most people to get there, even if they are writing various different things at one time. Which of course is the real point behind the theory. What it is really saying is that you need to put in consistent effort over the course of time in order to develop your overall skill, as well as your particular voice as a writer. There is a moment in the early stages of one's writing wherein you just sense that you have evolved from someone who likes to write, to someone that is a writer. And it comes with time and practice. Whether that moment is actually after a million words, a billion words, or 500,000 thousand words really isn't that vital. "A million words" is a term, not a formula.
But yet I would amend the famous "million word" advise. I would add that you start to be a writer once you have reached a million words your own way.
I am not a huge fan of rules, especially for writing. I think some of the best writing out there is the best because it broke, or at least ignored the rules. I ignore plenty of them myself. Still, there are in fact some rules for being a good writer. You have to read all the time. While perfect grammar isn't crucial, coherence is. Any given piece should probably not alternate between two languages at random. And a few other pretty strong, and sometimes obvious foundational rules of the craft do in fact exist even to a rebel like myself.
But truly, many writers of all stripes get too tied down with too many rules. So for your first million words forget rules. Just write. Write everything. Write on blogs. Write fiction, even if you are not a fiction writer, and write non-fiction even if you consider yourself a fiction author. Write everything, whether anybody reads it or not. Just make sure they are a million of your own words. Not a million words as your professor would have your write them. Don't worry about the rules for a while. Just write a million words, however long it takes you, and pay attention to nothing at all but what speaks to you. (Don't even pay attention to whether or not you have reached a million words. It's a metaphor people!)
So yes, screw the rules. If really long "run on" sentences speak to you, write in those. If you like short, choppy repetitive prose, write a million words of that. Use adverbs all the time. Include cliches and lists. Switch between view points within a single page. Put down a million words in whatever way you want no matter how many English professors are sent to the asylum as a result.
Because the first thing a writer needs to learn is to trust that he/she can in fact write. Not write according to someone elses ideal, but write according to what speaks to you. Anybody can learn to write a million words according to every rule in the writer's guide book. And in the end all you will have is a firm grasp of the boring rules followed by other people. But if you set out on your writing journey with the intent to ignore the rules and write all the time, you will experience something far more important than mastery of a format; you will experience an understanding of what you want to say, and how it is you want to say it.
And then an amazing thing will happen. You won't know why it starts to happen when it happens, and you may not notice it at first. Yet if you keep at it, and worry less about rules of writing as you get to your million words you will suddenly find that somewhere along the way you slipped right into the ranks of good writers that follow the so called rules, without even realizing you have done it. You will take a good long look at your most recent piece, and compare it to one of your earlier ones, and find a world of difference you didn't even know was there.
Almost by magic, you will have adopted not only the few core foundational rules of writing, but also perhaps some of the stylistic rules as well. Yet you might not even be able to define what those rules are. You will just come to a natural rhythm in your writing which syncs it with all of the advise people have tried to give you over the years. But you will have maintained your own unique voice in the process. You may even find yourself ahead of those who spent so much time memorizing, learning, and putting every rule into practice over the same time period.
And the source of this magic? Confidence. All of the other "rules" of writing are bogus if you do not become confident in your words. By writing, and writing, and writing and writing, and getting to a million words on your own terms two things happen. First, as I already said, you come to an organic understanding of some of the universals of writing. They are not universal because someone said so, but universal because passionate, confident writing tends to reflect them naturally. (It's a mystery. Enjoy it.)
But perhaps more importantly you will have practiced the art of trusting your own voice. Of relying on your instincts and speaking from within the deepest part of you. That concept I assure you is ten times more difficult to master than any skill specific to writing itself. But once you have mastered it, you need fear no more rules. You can even embrace them all if you like. Because by then, you will have become a conduit for your own voice through words.
Or, to put it another way, you will have truly become a writer.