I have just done this sketch getting to work this morning. I then quickly scanned it at low res. to check for errors. I really recommend scanning your sketches at early stages. The ability to flip your image sideways, zoom out so it becomes a mere 20X30px thumbnail is a great way of spotting issues that need fixing at early stage. (With this one – you can tell her right leg is too small compared to the other. It’s because I changed the perspective to include the ship with bunch of samurai marines running to slice her up real bad!)  From there, you can either:

- correct things within your software of preference, using your tool of preference (brush, selection marquee, transformation tools, etc.) and print it out for refinement,
- stay in the software to finish or;
- remember where you went wrong and get back to your sketchpad, as I will do since I do not currently have time for personal and I truly believe that you cannot spend enough time on a sketch.

Happy doodling!