Guillem March is one of those artists willing to share his process from start to finish. It's refreshing to see such openness, because the formation of an idea for a cover or interior can be just as interesting (and helpful to other artists) as seeing the pencils/inks/colors. So, with initial rough sketches included, here are March's Catwoman covers for issues #5, #6, and #7.
Catwoman #5 sketches, inks, and final cover
Catwoman #6 sketches, pencils, pre-editorial supervision, and final cover
(Below is the cover prior to editorial supervision. Note Catwoman's mouth.)
Catwoman #7 sketches, inks, and final cover