A few tips from the great F. Scott Fitzgerald, compiled from the handy collection F. Scott Fitzgerald on Writing:
1: Start by taking notes.
2: Make a detailed outline of your story.
3: Don’t describe your work-in-progress to anyone.
4: Create people, not types.
5: Use familiar words.
6: Use verbs, not adjectives, to keep your sentences moving.
7: Be ruthless.
If you can follow even three of those closely enough, you’ll be well on your way.