I've been drawing since I was 10-ish and even then I noticed my hands shook uncontrolably. I have since refined my art to mask the problem, but my art is such a scratchy mess. Is there any way to at least help with this? I want to be able to draw a decent line without looking like Michael J Fox took over my tablet.
-practice placing two dots on a page and drawing a straight line between them, going over that same line several times, gradually moving from a few inches to all the way across the page. Make parallel lines at different angles
-maybe get a brush pen or a think black pen when you draw. You only get one line so you have to make it count.
From my own experiences, scratchy, fuzzy or just generally unrefined line work comes from a combination of not having a full understanding of what you're trying to draw (could you envision every form and detail?) and a lack of confidence and control of your ability to make marks.
Get some pens and try traditional medium for a while and like the other anon said do some drills and exercises in making lines and when it comes time to work on something every stroke should be deliberate and planned. It will take a while to get good at because it's something you need to constantly working on but in the end it will benefit you greatly. https://youtu.be/wgDNDOKnArk
Have you considered using stabilizing software like http://lazynezumi.com/ ?
Various art programs like Paint Tool Sai and Clip Studio Paint also have a similar feature built in, but it's not as customizable.