The first image above shows me scribbling around, looking for an idea. As with most of these pin-up assignments and even some covers, the editor didn't have anything specific in mind so the concept was up to me.
The large drawing looks like I was trying to get a handle on her personality. The big fist below it looks like a leftover from another project. In fact, the sketches were all done on the back of a Batman: Sword of Azrael script.
I like the idea in the lower left; especially her body language, but figured I'd better show her face. The upper right drawing shows the idea I decided to go with although I dropped the pile of skulls behind her.