Originally Posted by
Utopia
My advice would be to take a role that really challenges you. One that it is difficult for you to put yourself in the shoes of the character. Something that you wouldn't normally play. Then write in that character's cadence.
For example, if you have a dumb characters, write in short choppy sentences that break up his thoughts/actions into simple statements. If you have an arrogant character, write in long monologues using big words and a condescending tone.
Written examples for comparison:
The Troll Thumpy Finds a Puppy (standard)
The Troll Thumpy Finds a Puppy (In Character's Cadence)
Now, neither example is the most stellar writing int he world, but which one gives you a better feel for the character instead of the writer? Sure, the second one sounds like it belongs in a child's book, but you get a feeling for Thumpy as a troll. They both basically say the same thing, but they say it differently and each gives you a different impression of the troll and the scene.
That is what you want to think about when writing in character. How does the style convey the scene and the character in it?