Well, best is to never let it go into the debit side at all. I have a Visa card and I always keep it a few thousand bucks on the plus side, that way I can use it to pay things without paying any interest or fees. And because its from Amazon its free and I get various % discounts when I use it. And it doesn't matter to store money on the card, since saving accounts in a bank don't pay any interest anymore nowadays.