If you are going to sell a device you should do the following list in this exact order.
1. Erase and reset your device.
2. List your device on the appropriate site.
3. Verify your device is reset.
4. Deliver said device.
5. Before handing off device make sure it is reset.
6. Go to Olive Garden with you recent business endeavor.
In all seriousness make sure your device is reset. If you don’t you will be handing off information to someone that you do not know. Also doing so will allow the new owner to actually set up the device to them.