Nothing's more disappointing than a wonderful character who doesn't have much to say. Writing dialogue that makes your characters come alive is critical to the success of any great story. Using dialogue to convey deeper emotions is where studying the actor can help your process.
THEATER SETS THE STAGE
My experience has been primarily writing dialogue. That's the part that comes natural and easy for me. I'm fairly certain it's because my background is in theater and I have spent years teaching actors to use dialogue to convey emotion and intent. My first three published books were collections of scenes for student actors with a fourth collection of scenes due out in August, 2015, and consist of all dialogue. But dialogue is just a tool to convey meaning. It isn't the words that are important, but the nuance and intent behind the words.
MEANING IS IN EVERYTHING BUT THE WORDS
The famous acting teacher, Stella Adler, once said, "Acting is in everything but the words." I love this quote because it sums up the difficult task of both the writer and the actor to convey feeling through dialogue which may or may not be a direct reflection of the character's intent. And that nuance is what makes the story interesting to the reader or, in the case of theater - to the audience.
CREATE AN "INNER MONOLOGUE"
For the actor, there is always an "inner monologue" going on and despite what he or she might actually be saying, that inner monologue is what's driving his intent. He/she may be feeling one thing and saying something to the contrary. This is what makes characters complex and interesting.
So, consider this - what your character is saying is not necessarily a direct reflection of what he's feeling inside - and that's good! That makes a character intriguing to the reader. The more nuance you can give your dialogue, the better. Of course there is a time and a place for direct dialogue that has little or no nuance, but be aware of the difference and write it deliberately.
LET YOUR CHARACTERS TAKE THE STAGE
My process for writing dialogue involves seeing my characters "onstage". Once I've made some basic decisions about them - age, physical appearance, temperament, etc. - they seem to take on a life of their own and I try my best to get out of the way and let them direct the conversation.
If you have been writing for any length of time, I imagine you've had this same experience. Your characters start talking to one another and you just do your best to keep up and write it all down. It's a surreal experience and very surprising at times. I write down what my characters are saying, even if it seems contrary to the direction I thought my story was going. I'm interested in what they have to say and I can always edit and redirect later. But what I find is that they are most often on to something interesting.
So keep in mind these tips when approaching and writing dialogue -
Good luck with your amazing characters!