If your card gets hit, cancel your card. Heck, even if your suspicious that your card details have been leaked via a website that you use, cancel your card. It's far less hassle to be a couple of days without a card, than it is going through weeks of back and forth with your bank, trying to get defrauded money back. Don't think that if you haven't been hit, or they failed to take money the first time, that they won't try again.
I try not to take chances, and keep my online presence to a minimum, deleting card details from sites after I receive good that I pay for, re-entering them if I need to shop there again, and still I've been hit over five times in last few years.