Never underestimate the power of the symmetry tool when it comes to brainstorming character designs. Programs like Sketchbook and Manga Studio offer these tools (providing both X and Y symmetry). Draw one side and your sketch is mirrored simultaneously on the other side. I use this technique quite a bit when I’m developing a series of quick thumbnails for concept work.
Inks: This is where I add some small variations in texture and some asymmetry to the design.