How do I decide which resolution to select when scanning from Epson Scan?

• The best scanning resolution depends on the purpose of the scan. If you are enlarging your image, you must increase the resolution (dpi) proportionally to maintain the resolution of your original.
  
  Higher resolution settings result in larger file sizes. For example, an 8.5 x 11-inch original scanned at 300 dpi can produce a 24MB file. The same original scanned at 72 dpi creates only a 1.3MB file. Large files take longer to process and print, so consider the practical limitations of your computer system when selecting a resolution. To keep your file size manageable, select the lowest possible resolution that gives acceptable quality.