The good way to go is via USB, dont't put anything on the SD Card Boot partion.
But for me the "simpliest" way to go is via Samba (Windows Share), you can enable it in the Retropie Configuration script but this method require a WiFi connection.
For the USB method, you need to follow exactly provided here (https://github.com/RetroPie/RetroPie-Set...rring-Roms), don't create other folder than 'retropie', for some reason if you add 'roms' and systems folder, sometime Retropie fail (occurs to me in the past)
Hope this will help
But for me the "simpliest" way to go is via Samba (Windows Share), you can enable it in the Retropie Configuration script but this method require a WiFi connection.
For the USB method, you need to follow exactly provided here (https://github.com/RetroPie/RetroPie-Set...rring-Roms), don't create other folder than 'retropie', for some reason if you add 'roms' and systems folder, sometime Retropie fail (occurs to me in the past)
Hope this will help