This is a piece I was commissioned to work on, as a cover for a tabletop game (Paizo's Pathfinder) adventure book. The theme included a young looking psychic woman, within the confines of a library. She was posed to reveal the future to the viewer, in a calm and knowing manner. Cultural directions touched the gypsy element, though they needed a slightly "sexier" outlook.
I didn't use any reference for the posing or composition, deciding I preferred to doodle my way through no-gos until I hit the spot; which, admitedly, is a pretty straigh-forward setup. The light should clearly focus on her, and through working on that I veered toward an inner radiation kind of feeling, ever so subtle. I kept the background dark and made the figure pop out quite clearly.
The final piece, after a few color tests, was this:
For the face specifically, I used a model reference, for the aim was to keep an overall realism to the piece. With slightly different eyes and hair-style to the original, the end-result satisfied me and client alike.
I also referenced her left exposed arm, and also had to shuffle through a number of intricate jewlery designs, all the while keeping it simple.