1) Write every day, except when you're in surgery or labor or a coma. Set a daily quota--250 words, 500 words, 1667 words, 8,000 words, a scene, a handwritten page, or whatever fits your life and writing rhythms, but set it and keep to it until you've drafted a novel. After a draft is completed, take a break of whatever length you need (most people take at least a month, to gain some distance--you can write on another project during that month or do business). Next set a daily quota for revising that book. Then, after revising, you can take another break for your creative well to refill and, when it has, you draft the next book. (If you're one of those "I only need one day to jump back in" people, I envy you. If you, like me, need some weeks to recover, that's fine, too. We all have our own rhythms.)
2) Read books on craft. Writing is a craft. Talent is not some magical spell taking root in your brain without effort, or inborn like your eye color, but is you learning skills, practicing skills, and getting steadily better. Magical granting of talent may sound like more fun, but here in the real world, good writers work to get better. Particularly early in your writing life, how-to books will shorten your apprenticeship. Years after my first pro publication, I read Story (McKee) and I still learned something.
3) Read good fiction--the award winners in every genre, the popular books in your genre of 25 years ago and 10 years ago and today, and everything by the writers you love to read.
4) Analyze your favorite books for their craft. Count words in sentences in slow scenes and actions scenes and compare. Circle verbs or characterization by description or whatever you'd like to learn how to do better. Highlight action, introspection, and dialog in different colors. Study these mark-ups and come to conclusions about craft from them. Figure out exactly how that book became your favorite, and take those lessons back to your own writing.
5) At some point in your writing life, not when you're new, not when you're consistently being published, but in between those two points, critique other writers' works, in a real-life local group, or online if you can't find a face-to-face group in your area. You'll probably learn more from detecting others' mistakes and figuring out how to fix them than you will from listening to critiques of your own work. (And don't worry if the other writer doesn't take your advice; the point was to learn for yourself how to detect and fix those mistakes in your own work, after all.) Switch groups every couple years, too, for the friendships that develop will make the critiques less honest. (Keep the friends, but switch groups.)
6) Don't write to be rich (chances of that happening are little better than winning the lottery). Don't chase publishing fads. Don't write to impress your professors. Write what you honestly like to read, what you can write with joy on a daily basis over many years, and have faith that your audience will find you one day.
7) A good style is one that makes you invisible, not one that draws attention to you.
8) Accept that it may take, as Gerrold says, a million words of practice writing to write a good novel. I hope it takes less, but if that's what it takes, you're not abnormal. Learning to write is, in this sense, much like learning to play the violin. You're not going to be the soloist at the Big City Philharmonic after one or even five years of practicing your fiddle. Be patient, and do your work.
9) Protect your love of writing. If you always end up broken-hearted after talking to X person about writing, or after logging 100 agent rejections, or after reading your one-star reviews on Amazon, quit putting yourself in the way of that pain. As the old joke says, "Doc, it hurts when I do this." "Then don't do that."
10) Read advice like this list if you like, but take all advice with a grain of salt. All writers give such advice out of their own experiences, or out of that of their close writing friends. Your experience may end up being nothing like mine.