1. Learn the date of original purchase.
Check files for download dates or any other time indicator to be able to determine how much the tablet has been used.
2. When possible turn the tablet on in the store for an extended amount of time.
The more time you have to run the tablet (20-30 minutes if possible) the better the chance you have to make sure the device doesn't crash due to problems with the battery or software.
3. Change a device setting or load a program.
4. Check for built-in Wi-Fi and/or Cellular capabilities.
If the tablet has cellular capabilities, buy one that will take a sim card that can be used on the AT&T or T-Mobile network as those sim cards can be changed. Verizon and Sprint sim cards can only be used on those networks.
5. Check the internet for the price of a new tablet.Are you saving enough money on the used purchase price to justify buying a used tablet?