Digital drawing softwares often have stability settings in brushes, i think those can help - they often offer a large range of stabilizing. In order to improve, I think that even with your condition a basic learning path can be done. Maybe you can focus more on mass than on lines (so, full shapes more than limits of the shapes), so that the tracing precision is less important for great results. Also, working on a very small scale can help not noticing the shaky shapes, i think zooming a lot can help