Inking is the part of the process that is both tedious, time consuming, can still be fun (unless you mess up and have to start over...yep, no erasers with ink). I have heard many people in the art world say that inking is not a necessary part of the process for what I'm doing it for. The truth is, I've skipped this part a few times, and it basically created even more tedious work for me later by not inking out the image. So, I ink.
What inking does, is that it makes your artwork solid, precise and ready to be scanned into the computer. The step after inking is illustrating the piece. I use Adobe Illustrator for this step and I can tell you first hand, if your lines are not dark and solid when you scan the image in, it's going to be a pain in the ass for you later. So I would suggest you ink that shit out.
For me, I like to use a light board (portable type light table). This allows me to trace the sketch when I ink. I do this for a few reasons.
1. It allows me to ink the sketch identically.
2. It lessens the probability of mistakes that would cause me to have to start over. If you don't have a light board, don't worry, you can also use a window with the sunlight shining through.
When inking your drawing, I would suggest not using ballpoint pens. A ballpoint pen will leave the same color variation as a pencil when scanned and cause some grief later. I use Prismacolor drawing/cartooning pens. These come in various thicknesses that will allow you to do thick lines, fine lines and everything in between. They are also fairly inexpensive.
If you do not have Prismacolor pens or can't get them, another option is Sharpie. Sharpie makes the thick markers that you're used to seeing but they also make thin pens as well. These are also inexpensive and can be purchased almost anywhere.
After you have inked out your drawing, it's time to move on to the next step.