To avoid gift card de-activation, ask for a receipt and make sure the gift card is bought with cash.
Watch out for card re-sellers. If the card was obtained from 3rd parties there is a risk that card becomes invalid during or after the trade. Ask everyone to provide a picture with your username and trade ID.
Be careful when accepting e-codes or gift cards bought with debit/credit cards as any debit/credit card purchase can be charged back.
First, make sure that the buyer’s account is verified on that wallet (i.e verified PayPal account)
Ask for the ID of the buyer. Make sure the full name matches on both the ID and the online wallet account.
Note that it could be easily charged back since every payment is tied to a debit/credit card. If you want less risk, make sure that the buyer is sending the payment from their PayPal balance instead of a debit/credit card.
Make sure that you are trading with the owner of the account and no 3rd parties involved.
For extra precaution, you can ask the buyer to write, on a piece of paper, the confirmation of the purchase of bitcoins along with the trade ID, amount, and that the payment as final. You can then tell the user to take a picture of that. In case of a chargeback, you can show it as evidence.
This method is just as risky as online wallets as you could easily be charged back. The tips for avoiding the risks for this are the same as online wallets except that the name of the debit/credit card has to match with the one on ID.