Teaching Writing to Middle Graders

I've had an awesome opportunity, twice now. My mom's cousin's granddaughter LOVES to write. She is twelve years old and is really talented, actually. For her birthday, her grandma asked me to give her several one-on-one writing lessons, and I have to say, it's been a BLAST!

(Isn't that a great birthday gift?)

I wasn't sure how to go about it. Where should I start? I knew I wanted to do some free-writing with her, using prompts. I knew I wanted to cover the basics of characterization, descriptio...