Welcome to the forums BPK! I'm also an eager manga enthusiast, I think you'll have a good time in the forums and learn a lot from the community!
We also just started a comic/manga forum in the art school discord where you can find resources, videos, works from some of us, and much more. Highly recommended if you want to dwell more into it.
Discord link to the comics/manga section:
https://discord.com/channels/371283268215242784/1245965680168140821
On regards to smooth lines, everything others said is pretty useful. It's usually a combination of line confidence, technical knowledge on line weight, brushes and practice.
I can share what has worked for me for now:
1) Unless you are adding fine detail, make sure to do long strokes for your lines using your elbow and shoulder. The hand can only rotate so much so you end up with little "scratchy lines", but by doing long motions the overall line should have a nice flow to it.
2) In general, I end up doing 3 layers. One for the initial draft or idea, usually very crappy, but just putting the idea on paper. Then the actual detailed and drawn sketch, usually with bad lines, but overall well drawn. Final layer where I'm just "tracing" my detailed sketch, but focusing on making the lineart as pretty as I can.
![](https://d1s0ws440m13mk.cloudfront.net/original/4X/9/8/d/98dc24ec8e6ceff16a3b200a71d4d4a2ba44e617.png)
3) Make it a habit of undoing lines and repeating them until you get that "right perfect line". Shortcut your undo key to something you have at your finger, then draw a line, if it's not good, undo, repeat, and repeat this a few times until you're happy with the line and move on to the next one.
4) Don't worry about going beyond the limits with your lines. I personally find it easier to erase line excess, than to get the line perfectly in one go. I'll also redraw over an existing line if I feel it needs more "weight", and then erase excess as needed.
5) Patience!! Most of the steps above might seem like a lot to just do a simple drawing, but as you get familiar with your pipeline, you get more comfortable and faster at doing it.
Other than that, I recommend looking at what other artists videos recommend, trying it out, see if it's working for you, and if not, move to another one. Keep experimenting until you find something that works for you. If you don't experiment or try things out, it'll be hard to find a solution that works specifically for you.
Here are a few to help get started: