I am a newcomer who is trying to convert an old black-and-white sketch that I made using a mechanical pencil into a vector layer that will eventually be used as the base line-art for a full-blown color illustration. However, because I made the mistake of folding the sketch to make it easier to store in a drawer, the surface of it is now covered in these really big smudges, creases, and blemishes. The "Remove Dust" tool has no effect on these imperfections. In addition, I noticed while I was experimenting with the "Convert Layer" tool that it has the rather unfortunate tendency to overlook variations in line thickness and make the thin lines disappear, as well as how easily this tool can eliminate curves and fine details by mistake due to the rather ambiguous design that its interface has.

Any tips, suggestions, and possible workarounds you could share on how I and artists who are in a similar situation could address this dilemma and use these tools more effectively and efficiently would be sincerely appreciated.