5. What do you consider the most important principle of fiction?
This is a good one, and I'd love to start a discussion about it because I'm not sure I have a ready answer.
My first impulse is to quote Stunk & White: Be Bold. Be Clear.
But I'm not sure that's a "principle," per se. I know that when I was first starting out, I spent a lot of time arguing with other genre writers about the importance of clarity. Some people thought that it was more important to be clever. They thought my preference for understandability meant that I wanted to appeal to the least common denominator, sell my soul for commercial success, and otherwise abandon the craft.
For me, the issue was that I wanted to tell a story that would be heard/read.
Ironically, the people with whom I had this argument are also commerically published now, so I guess that in the end clever and clarity aren't nearly as mutually exclusive as I first thought.
But I don't think that's really what's being asked here. I think you want to know what aspect of the craft you should concentrate on the most: plot, character, or what have you.
My answer is still the same. In the interest of being bold and clear, focus on story telling in general. Maybe for you that means you need to strengthen your characters. For me, it meant learning everything about plot... (because that's my weakest area.)
What do the rest of you think?