Well in my case i either scan my sketches and ink them completely with brushes on PS, or ink them with nankin before i scan and clear up the lines (that may look croppy).
I found a good way nowadays, i scan my sketch in rough pencil, get it into photoshop, put its opacity at 30-40%, put its color at some tone of light blue and print it. The image should look like it´s erased, but still has some shadows to guide you on inking. After, i ink that printed version of the sketch with nankin, and that way, when i scan, i won´t have those smudges and wrong lines (and even those creases' shadows that sketch papers ALWAYS get ^^). I just have to scan it with a good resolution (300 is perfect, not more than 600 or less than 200 though). Then i go to Photoshop, put the mode into grayscale, adjust levels to make only the lines to appear (to take off those "blue" rests that may insist to stay in your drawing), and make heavylifting (search on deviantart for that, augustc4 did a great tutorial about). After making the heavylifting, i make a clean up on my drawing, making the lines look softer by using the eraser and a small brush. After cleaning up, it turns out in a final lineart, and so i can start colouring ^^
(BTW i´m trying out soft cell shading, that´s a really cool colouring style imo. And i neer start colouring until i finish the lineart)
This method may look complicated, but it´s just because i CAN´T use the Pen tool, as much as i try lol -_-
BTW man your drawings are simply amazing! I like your style!!