Ooooo. Awesome!
Reference image: http://media.tumblr.com/tumblr_lyy6hrSvLz1r0vgv0.png There will be a fair number of modifications on this, but it's a good baseline. :D
What color are their eyes, skin, hair, lips, etc: "Zali, on the other hand, was so dark brown that she could almost be called black, while her tar dark hair reflected nearly orange in the light of the sun. Her features, though, were fine-boned and narrow, unlike many of the dark-skinned companions she had traveled with in her twenty four years of life. The thing that made her stand out the most, though, were her pale grey eyes which, when combined with her dark skin, made her come across as a ghost or some sort of malevolent spirit."
What hair style do they have?: Most of Zali's hair is held away from her face by a tall ponytail, however she has several large braids coming from either side of the ponytail. Unbraided, her hair would reach about to her collarbone, while the braids would reach her shoulder.
This is the closest reference image I could find to what I was thinking, but it isn't perfect. Feel free to get creative!
What build do they have? (Muscular, thin, thick, etc.): Thin, but strong and athletic. She's an avid sailor and has worked on the seas all her life.
What is their gender?: Female
Make-up: None
Accessories: Her ears have been repeatedly pierced, with two sets on each lobe, and a bar/industrial piercing at the top of each ear. However, she never wears large or highly decorative piercings that could get in the way, or cause her to be at a disadvantage during a fight. She has a small bag at the end of a necklace, with a bone carving of an anchor sewn onto the front. This might not be visible in a headshot, though.
Now, how would you describe the overall appearance? (Nose shape, jaw shape, lip shape, eye shape, etc.): As I mentioned in the quote above, Zali's features are quite fine-boned and narrow, especially for someone of her heritage. The picture I offered is pretty good in that respect, except I imagine her cheek and jaw-line would be a little sharper.
What do you want them to be doing?: Zali is a very outgoing and active individual, so she's probably about to plunge into some new, dangerous adventure. A fierce or... feral expression could be kind of fun.
Background?: Water, a jungle, or a boat would be awesome, but no background is just fine. :D
Extra Comments/Side Notes?: Zali is a pirate, in a more historical setting. Golden Age of Piracy type era, in a semi-realistic setting. I don't know if that has any impact on anything, but now you know.
If there's anything you'd like me to further clarify, explain, or add to, don't hesitate to let me know!