3. Contrast reality. Dexter's not just a serial killer: he's a brother, a single dad, an employee of the Miami Metro Police Department, and a good friend. His personal life is rife with areas of conflict. By giving your characters more dimensions, you add more conflict to your story.
4. Secondary characters should have their own issues. In the series, Miami Metro is a hotbed of drama. Dexter and Doakes, LaGuerta and Angel, LaGuerta and Deb, LaGuerta and Matthews, LaGuerta and Dexter, Deb and Brian, Deb and Lundy, Deb and Quinn, Deb and Dexter. I could go on, but you get the idea. Real people have real issues with other people. Don't leave all the conflict to your protagonists.
5. Always leave your audience wanting more. Whether it's the end of a chapter, the end of the book, or the end of the series, don't become one of those writers going by rote. When you find yourself bored with your story or sensing you've done all you can with your characters, it's time to wrap it up.
Later this week, I'll post life lessons learned from Dexter.