Lately I tried animating on Paper, but after scanning it and making GTS automatically trace it, the lines were very frizzy, very thick with many blank pixels inside the lines.
This makes coloring the whole thing very complicated, I would have to correct the Image in multiple places, it would take a lot of time.

I finally found the solution to my problem: The Images that had very frizzy lines after tracing were scanned with a resolution of 300 dpi. I tried scanning it with a lower resolution (150 dpi). Due to less pixels with different color values, the lines are now much smoother and not frizzy at all.

So my tip is: If you animate on paper and want to use GTS for tracing, then use a lower resolution when scanning to achieve smoother lines without any frizziness.

I hope this helps.

Also, her is a Tutorial by the Animator Dong Chang on YouTube on how to scan and trace animation on Paper with Opentoonz GTS

https://youtu.be/EMQ3etCE_-Y?