If you want to be a writer, you must write. But on everything else, it’s not so black and white. Whether around the Internet or in a real life writing group, writers will offer you plenty of advice, much of it very good. “Read as much as you can” is good advice. “Do your homework on the publishing industry” is good advice. “Revise your writing before trying to get it published” is very good advice.
But for almost every piece of advice out there, you can find an exception. Some authors get published at age 18. Some can give a book away for free and still sell it later. Some can sell re-purposed fan fiction and that very successfully. Of course, most people will never do any of these things, and if you think you will be the exception, you might want to reevaluate. Maybe you’ll get lucky, but probably not.
The point is that (except for the prescription that you must write) you should take every piece of advice about writing with a grain of salt–including mine. That goes even more for any tips a writer gives you about how they personally perform their craft. Every writer is different. For example, you may like to write by the seat of your pants, while I like to outline a story before I start. (Or, at least, I think I do. I’ve never quite done it properly.) And that’s only where the differences start.
Publishing is even more complicated. The Internet has made self-publishing so much easier that it’s upending the whole industry, yet the bestsellers still come out of the traditional publishing houses. I don’t think anyone really knows where publishing is going in the future.
So what should you do? Well, this is yet another piece of advice, but I recommend doing your homework. Read plenty of published fiction to figure out what makes some books (in your estimation) better than others. Look at advice from different sources; If you don’t agree with something, try to understand why it is recommended and why you disagree. Then figure out what works for you. It may take a while–I’m still learning, myself–but when you do, you’ll be in a pretty good position.
And, as always, keep writing.