Make sure the scanner is super clean so no dust, hair, etc. appear on the scan. 600 or even 1200 dpi is ok. I usually scan at 1200 dpi, clean the scans at that level and then bring it down to 300 dpi. Make sure your covers are flat on the scanner. I usually set a bunch of books on top of the cover when scanning. If your scanner offers noise reduction, use it. JPEG is fine.