If you have restaurant cards or cards you can only use in-store, it's important to make sure you actually have them with you. There's nothing worse than checking out and realizing your $50 gift card is at home on your kitchen table. Also, consider using mobile wallets like GoWallet, Apple Passbook or Google Wallet, so you can use your smartphone to pay. Sometimes, it's a lot easier than stuffing your wallet with plastic gift cards.