Now that I really have your attention...
Tip: review your bank account balance online once a day.
Tip #2: keep your receipts until you verify completed transactions in your account.
Tip #3: shred your receipt afterwards.
Why the first tip? Because you never know when you'll have a charge for $1,215.54 plus another charge for $27.33 in a hospital in Mexico such as I had today. Fortunately, I called ING right away, canceled my card, and filed a dispute. The problem is the process is quite onerous - it could take up to 45 days to fully credit my account, plus I might have to submit supporting paperwork.
The woman I spoke to on the phone said it's unlikely I'll have to submit any further paperwork because I was calling from my phone in Connecticut and the charges in Mexico were showing up as recently as today (and unless I can be in two places at once...) so this should put an end to this mess.
And why the second and third tip? Because you never know when the few horrible people in the world are trying to rob you (such as whoever used my card number at the Mexican hospital) or when they're going through your trash to get your account number (that didn't happen in my case, but it's good advice to shred receipts regardless).
Finally, my last money management security tip... have a backup bank account and/or carry some cash at all times. Fortunately, I have a second checking account where I'll be able to withdraw money while this account is canceled and until my new checking card arrives. If you don't want to maintain a second checking account, make sure you have at least some cash on you at all times because you never know what might happen!