The Champions League

work at a large size and don't save at a smaller size. You work at a larger size and save at that size. This is your original work. Usually 3 times the original is good. (unless you are doing a large poster or advertisement, size accordingly). When you export the drawing to a new file to be published, you resize that copy. This way you keep the original. There is no way to resize down without destroying information you will never get back (unless you use vector art but that is a completely different thing). DPI has zero to do with digital when you size by pixel, that is a print thing. If you image is 300px across, 75, 150, 300, 600 etc dpi means nothing unless you print it. You can't hide 300 dots in a 1200 px across drawing. The drawing is only 1200 across, that is it. The only thing that will happen is when you print it, the image will be physically very small. The resolution will be the same.