When you look at some of the writing advice out here in the great etheric wonder that is the internet, what you'll see is a lot of the same information repeated over and over. This is because writing isn't a science, it's a very subjective process which looks similar to lots of different people, but with a few common factors which tend to influence the craft in immensely different ways. One of the big ones I always see is READ. And yes, it is a big one. Huge, even. Top two or three. Because...writers tend to also read. But for my dollar, there's one that takes the number one spot just above reading (number 2), and actually doing the writing itself (number 3). Yes, even above the writing. Why? Because the best way to learn to write is to read. That's all well and good, I assume you say, but what's number one? Well that leads us here, to the element of writing residing at the number one spot is:
Revision...Learn to Love it:
I know, I know, right? Kinda gave that one away. But the importance of this can't be overstated. Other writers will disagree with this in slight terms of importance. Learning to love and appreciate revision and editing is where the REAL writing happens. Writing, especially longer works, is not a one and done type of thing. Unless you are a one in a billion (with a 'B'), chances are you don't write something down and it comes out as if uttered from the lips of God. You make mistakes. There are typos. Information and back story is missing. Your characters aren't developed. Your bad guys are flat. And most of all, your writing probably sucks.
Don't take that last part personally. My first drafts suck big hairy, dangling, goat...appendages. I'm editing one right now, and it's the kind steeped for days in a mixture of vinegar made from raw sewage and second-hand baby diapers. So there.
So why learn to love it?
Because, as said above, it's where the real writing happens. Writing is called a craft for a reason. It's likely that your words will need to be crafted and shaped into something better than when they originally dribble out of your mind and through your fingers to make sloppy, magical brain juice on paper you may or may not have found in the vicinity of a toilet. In fact, most first drafts can hardly be considered magical, just about any author will tell you that. But the shaping, from barely formed clay into a gracefully sculpted, uh...sculpture, of finely hewn words, metaphors, and analogies, doesn't happen in one go. Heck, it only happens over time and experience with your story, and understanding the important things it has to offer.
So when you think about your writing and all these brilliant pearls of narrative glory that spring into that creative muscle precariously perched atop your neck, remember that they probably aren't great yet. But they will be soon, once you take the time to cut, shape, polish, and perfect your way into a true writer's work.