As I spend more and more time focusing on becoming a decent writer, I spend more and more time being grateful for all the years I spent as an actor and a director in the theatre. I had never given it much thought, but upon contemplation I have realized my theatrical history has given me many advantages.
As an actor I spent years (and I do mean years) getting inside other people's heads. I've played career-driven women, women with relationship issues, women hungry for power and women looking for love. I've even played a man with emotional troubles; it was the psychiatrist Martin Dysart in Peter Schaffer's classic play Equus. I learned all different types of dialogue, from comedic to tragic to Shakespearean. I honed my sense of comedy. I learned how people react to different situations and how to portray that (both emotionally and physically) on stage.
As a director I learned to 'look at the whole board' instead of concentrating on one specific piece. I learned to ensure the pace was swift and the interactions between the characters were real. I learned how to build suspense or how to make the most of a comedic moment. I learned when people should be quiet or when they should be loud. Most importantly, I learned how to make the play a cohesive whole.
All this experience has made writing much easier. I can get inside each of my characters' heads and look through the world through their eyes quite easily. I know what vocabulary each of them use. I know their rhythms. Most importantly, I know what each of them want. My directing experience has helped me look at my WIP as a whole, and aided in my knowledge of when the plot has stalled or the pace is dragging. In a play every scene has to move the plot forward and I try to apply this rule to my writing. Every unit has to either move the plot or let the reader learn something new about a character (or characters). I try not to have large descriptions of settings, unless it's vital to the plot. Many times it's the people and the events that are important, not the colour of the paint.
Every actor learns how to discover their character by the phrase "what do I say about me, what do I say about others and what do others say about me". Take a look at whatever you're writing at the moment and apply this. It may change how you view your characters or it may help you realize you're writing it exactly the way you want!
In the theatre instead of saying 'good luck' we say 'break a leg'. In that spirit, to all you writers I say 'break a pen or keyboard'.