There was a lot more to the reference photo: in it she's got a foot up on a stool and is leaning forward to pull a gun out of her holster.
Not a big fan of costumes when it comes to life drawing. If she were an actual cowgirl, or if I were illustrating a book on the Wild West, okay, but otherwise it's too stagey for my liking.
So I painted only the part that interested me: the head.
Though, I have to say, I would really like to have a model reading a book, dozing in an armchair, or stepping out of a clawfoot tub!