Rule #1: READ
Read everything and anything you can get your hands on, especially when you're young, scrappy, and hungry. Why? Ray Bradbury may have put it best, in his excellent Zen in the Art of Writing: Essays on Creativity, when he wrote, "Good books teach you how to write, bad books teach you how not to write." Nuff said.
Rule #2: WRITE
Writers write, obviously. Thing is, it does not matter when you write, or how much you write when you do. Daniel Jose Older has already taken the destructive advice to always "write every day" and stomped it flat, then ground it into the dirt.
Look, it does not matter if you write 500 words a day, 500 words a week, 500 words a month, or only 500 words a year. As long as you're taking a moment out of your busy schedule, and each and every one of us gets the exact same number of hours each and every day, to write something down, you are a writer. Welcome to the club.
Rule #3: THERE ARE NO RULES, ONLY GUIDELINES
Whether you outline, or you improvise your way through the whole damn thing, matters not. Nor does waiting until you have a finished first draft to begin revising. Lots of writers revise as they write, so that their first completed draft is pretty much their final one. As long as you are following the first two rules, you'll be inching forward. Over time, and via trial and error, you will figure out what writing style works best for you; and that is all that matters.
I believe my favorite motivational quote of all time sums it up best: "There is no path in life, you make the path." Don't know who said it, or if I am even getting the quote right, but I think the way I remember it is spot on.
Now go out there and blaze your trail. Maybe or paths might cross, some day.