For example, how do you write a villain that is not two-dimensional? Do you give you villain a "human side"? Or, harder still, how do you write a hero that has flaws and is likeable?
In my first attempt at writing- the epic Rosaline...*cough cough*- I gave her so many flaws that in the end, when she was shot (yes that's right, I shot her in the end of the book), I was glad to see her go.
Its a careful balance. How do you keep it in check? Who are some of your top villains or heroes?