Hi, Chiya-chan, you can call me anime artist, I guess. 
Some of the stuff that I’ve read before on lineart, you can actually get clean and soft lineart via different ways, though I believe doing your lineart on a computer software like Photoshop, Painter or OpenCanvas would be the best. I’m a photoshop user, so I’d say you can use the pen tool to draw out your basic sketch which you’ve scanned in. This doesn’t require any tablet pens. Another way is to use the brush tool to draw out manually.
If you’re not acquainted with using computers to draw, then you can do your best to do a clean pen inking over your pencil work.
Hmm, many have already provided links for you above, so you can go look around. Use the dodge and burn tool sparingly. I think it’s most professional if you can actually pick out your light and dark shades on your own instead of relying on these 2 tools. That’s my opinion.
If you want to know, I started drawing manga style around 4 years ago, and I didn’t have any basic drawing foundations. You could say my proportions and stuff were very bad because of that. But I’ve been studying in a design school for a few months, and drawing’s one of my modules. I’ve improved quite a bit and am happy that I can finally draw better. It’s best to pick up life drawing because you can draw the human body much better, and draw it in different perspectives and get the basics right. If you don’t plan on taking up classes, you can always do your own anatomy studies.
It’s great to have the best of both worlds… I incorporate life drawing stuff into my anime/manga style so it’s sort of like a mix (which i hope is good). Good luck~