It comes down to your drawing software and your printer. Before I print I clean my inkjet printer and and make sure the ink cartridges have sufficient ink. My software package I use can render nice circles for roundals at 800 dpi. Then raster it to a printable image. Save your decals to a good image file format. gif files loose some detail, Jpg files with minimum compression work well. be sure to use 24 bit colors and not 8 bit colors. After you print them you need to give them plenty of time to dry, then seal them. Finally cut the decal paper as close as possible to the printed area when applying.