HA I SUCK at lineart. I'm the one always asking good lineartists how they get their work to look so good, usually digitally, with a tablet, nice lines that I just can't replicate.
I actually used a ballpoint pen. Serious. Make a copy of the sketch, trace the lines, go over back and forth where you want to be thicker, just a few strokes for the thinest lines, etc. Then scan it in, and I use Manga Studio settings to pick up only the black lines. But I'm sure you can use another program to pick up only the black lines for uploading and coloring.
But yeah. Don't ask me...there are way more people better at lines than me. I have to use a ballpoint/fineliner cause I suck so much at digital ink. And even my ballpoint/fineliner lines suck monkey. xD