Sometimes, two seemingly unrelated worlds have more in common than you realize. Consider the worlds of writing fiction and acting.
To some extent, writing fiction is a lot like acting. When you’re writing fiction you’re also playing a role, or rather, many roles. Part of your job as a writer is to immerse yourself in these characters. To know them with a great degree of intimacy and, most importantly, to guide their actions in a way that feels natural and believable. You’re trying to convince your audience that these are real people facing real obstacles, not pawn’s in the author’s plot.
So part of being good at writing convincing characters is the ability to be a good actor. You can’t just write yourself. You can’t even just write variations on people you know. A good actor should be able to convincingly play people diametrically opposed to everything they believe in, even someone of the opposite gender. The same holds true for writers of fiction. You must have the ability to become the villain, or the abused wife, or the frightened child, or the crooked cop, or the world’s last honest politician, or the reptilian alien from Virmox-9, or whoever.
You get yourself into the head of your character as best as you can. You be that person. And write. If you’re not sure what words to write or phrases to use in their dialogue, you fake it.
In other words, you act.
What does all this mean? Aside from the obvious, it also means that writers can learn a lot by watching great actors. Watch Peter O’Toole’s masterful performance in Lawrence of Arabia, paying close attention to the way in which his mannerisms say just as much about him (if not more) as his actions and dialogue. Pick up pieces of Bill Murray’s understated performance in the overlooked Broken Flowers and incorporate them into your work. Revel in the larger than life way in which James Gandolfini stomps around the set in The Sopranos and consider how it can translate into one of your own characters.
If you want to write convincing characters, you’ve got to be those people. You’ve got to be an actor.