I've already posted about how roleplaying games have fed into my writing skills, but I got to thinking about other skills I've picked up, and where they came from. One of the concepts that has served me well with characterization is that of metagaming.
In a roleplaying game, you have in-character knowledge, or things your character knows because he or she learned it. You also get a lot of out of character information, such as party dynamics, secrets other players elect to share, secrets the game master shares with you, or any other knowledge you haven't learned in the course of playing your character. Bad players will mix these up, and use knowledge they gained while they weren't playing their characters to their benefit. Good players will keep any information gleaned this way out of their characters' heads. They may seek to reconcile what they know as a player and what the character knows by leading the character into situations that allow them to discover this information, but they'll accept the GM's decisions in how much is revealed in the game.
An example of this is, in a superhero game, characters may split up to cover more of a city patrol, and something happens to their communicators. One patrol may encounter a threat that's too much for half of them to deal with, but that one of the other characters has the skill set to defeat. Tension is ramped up by keeping them separate as long as possible, and a good GM will time the appearance of reinforcements to the best dramatic effect. The characters, meanwhile, won't go rushing off to save their comrades until the GM tells them they know something is wrong.
How does this relate to good storytelling? Think about the most suspenseful stories you've read. Think about the times when you knew something the characters didn't, which increased the tension, maybe even made you scared for the characters. Narrative tension is ramped up when the characters act on the information they have, but the reader recognizes that's inadequate.
I may have figured out how much more interesting stories are when I know things the characters don't without roleplaying. I am, however, grateful to my roleplaying experience for teaching me this basic facet of characterization.