Here are my 5 Rules about writing as taught to me by Life.
1. It's a job. Treat it with the respect, dedication, and seriousness that you would an outside-the-home job. That means putting in the hours, acting professionally in correspondence, and being mindful of who is out there reading, listening, watching...
2. There will be some people who will try to discourage, disparage, disagree, disapprove, disavow, disconcert, discredit, discriminate, disgrace, dishonor, disgust, disillusion, dislike, dismiss, disown, displace, disrupt, disrespect, disregard, dispute, distance, distort, distract, distress, distrust, and disturb you. Don't let them. Let them discover, discuss, and distinguish you. Your attitude should be pro YOU, but never at the expense of others, even if they are wrong.
3. School never ends. Just because you got that B.A. or M.F.A. doesn't mean you're done. Did you know everything before moving out on your own? Getting married? Having a baby? Life changes and you've got to learn new things all the time. So too, with writing: latest trends, what editors are looking for, which agent would be the best fit, what to chop and revise, which POV works. etc. are things that you have to stay on top of.
4. Copying isn't flattering-or legal. Don't try to be someone/something you're not. I love Sherrilyn Kenyon's, or Anne Rice's books, but copying them means denying my muse. Plus, it might invite a Cease and Desist Order. You want to leave your mark on the literary world-not hide in the shadow (however great) of others.
5. You won't always win. Books get rejected or fail to sell, agents and editors cut you loose, reviewers tear you down. It's akin to getting sick, or fired, or breaking up. Bad things will happen, but life, and writing, go on. Keep going, don't quit.