Jocelyn K. Glei offers 25 writing tips from famous writers. I have summarized them below, but I encourage you check out Glei's post to find the writer who offered the tip.
1. Sit down and do it.
2. Plunge in
3. Find your routine
5. Find a subject you care about
6. Keep your thoughts organized
7. Have an outline
8. Get through the first draft as quickly as possible
9. Be disciplined
10. Be willing to write badly
11. Be without fear
12. Don't look back
14. Always have multiple projects in your head
15. Don't hang out with people who do not support your writing
16. Take feedback seriously
17. Ask a friend to read your work
18. Think of other's success as encouragement to yourself
19. Know when to stop
20. If you get stuck, get away from your desk
21. Don't let things get out of control
22. Don't quit writing when the going gets tough
23. Keep at it
25. Don't get caught up reading advice about writing. Write!
By the way, the authors of these little ditties include Joyce Carol Oates, Cory Doctorow, Annie Dillard, Margaret Atwood, Neil Gaiman, and Kurt Vonnegut.