An iPad buy back can potentially provide you will a nice sum, assuming that your unit is still in good condition. Improve your chances of having a high appraisal.
The main thing is to act quickly since tech products depreciate year by year and month by month. If you decide to do this, then complete the transaction within the week if possible.
Clean up the device so that it looks presentable. Some people use cotton and alcohol to wipe off dirt on the surfaces but you can use any suitable cleaning solution. Keep it protected from scratches.
The store will check the functionality of the device. As long as you keep it away from moisture and shield it from impact, then it should pass this with flying colors.
Lastly, some stores will appreciate you bringing the entire box and original accessories, as well as the receipt.