How can I improve the quality of the output of Potrace?
The most effective way to do so is to improve the quality of the input! This seems obvious, but not everybody thinks of this. Scan your image at a higher resolution. Scan your image in greyscale, and use a program such as mkbitmap to generate a high-resolution bitmap to trace. In some cases, it also helps to decrease the resolution of the input image. If the resolution of your input file is incredibly high, the output generated by Potrace might be larger than necessary. This also sometimes happens if the input is speckly or noisy. Rather than trying to simplify the vector image, it often helps to just downscale the input bitmap.