|A lot. The answer is a lot.|
The truth is, there is no magic bullet, no special formula, no big secret. Sorry, guys. No there are no shortcuts. The truth is, almost everyone can write. You just have to make up your mind to do it.
But what separates the successes from the failures? That's a different story. A lot of factors go into whether or not one "makes it" in this business and a lot of it is decided by your own definition of success.
There are a lot of little things that go into a success story but I feel like the three most important aspects are as follows;
I turned professional in 2008, when I won my first NaNoWriMo (if you haven't done that, you should). I did not start seeing traction in my career until 2015. That's almost ten years before I started seeing any tangible results. I'm still nowhere near where I want to be, but I have no intention of quitting, either.
Forget what you've heard about the overnight success story; there's no such thing. These are people who toiled away in obscurity for years before finally writing something that resonated. Your first title probably won't succeed. Neither will your second. Or third. Maybe not even your tenth.
But all this time, if you're learning, improving, and building your network, then these aren't failures; they're investments. The good news is that these investments do pay off, but the bad news is they take a lot of time and energy. So lower your shoulders and get ready for contact, because this is a long, rewarding road.
WRITE EVERY DAY. There are arguments for and against this, I've tried both methods, and I've reached the conclusion that the only way to get better is to stay immersed in your craft. Write every single day. It doesn't have to be Shakespearean. It doesn't have to be anything anyone will ever read. But put words on paper every single day. Get in the habit of bringing your ideas into the real world. You'll see the quality of your work steadily improve. The Zone will be easier to slip into. Your good stuff will get better.
Stay in shape. Write every day. Allow yourself one or two days every couple of weeks to let ideas simmer in your mind, and then stay focused.
Far and away the most important aspect, and the hardest lesson to learn. I used to think humility was a lie, and I wish I could get that time back. I would have done better, sooner.
Not trying to be mean here, but you're going to suck when you first start out. It's not your fault. Even the most natural talents require refinement to be realized. Your work, initially, isn't going to be that good. You're going to write something that may offend someone else and they'll have no problems telling you about it (by the way, never snap back to a negative comment or review). Your first few years in this business will not be easy. If you're doing this right, you'll spend a lot of time learning, unlearning, and relearning as you find your groove. If you treat this as a business you may yearn for the days when you could just write. It all serves a purpose, which is to improve your craft, which in turn allows you to produce better work, which in turn allows you to grow your fan base and God willing, your income.
Never, ever assume you've learned everything. Be prepared to admit, publicly, when you're wrong. Don't be afraid to make mistakes. Failure is not screwing up. Failure is refusing to try again after you have.
Good luck, happy writing, and thanks for reading.