1. Let your characters be who they are, not who you want them to be.
2. Rewrite. Stories are like adolescents. They have an awkward phase before they become who they are really are. Give them a chance to change into themselves.
3. Read it, in your head, and out loud. I think reading out loud really helps me find the voice in a piece. And it sounds different out loud. It really helps polish a piece if you hear it both ways.
4. Be inquisitive. Writing is a way of life. It's a perspective that you take with you day to day as you walk around. Writers are people who notice details or truths around them. They paint the world for readers through words, and show us what we can't see.
Feel free to leave your own rules in the comments section or follow the link to post your rules at Cheryl Klien's original post.