I advise not to use debit cards at all. There's too much risk involved, since cash comes directly out of your checking account.

I had a friend use a debit card at a take out place once. They accidentally significantly overcharged him when they went back to put the tip on (so he never saw the receipt). They took out a pretty significant amount of money; had he not caught it in time, he would have been bouncing checks.

Unless you have some utilities or such that only accept debit cards, I'd stay away from them.

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