Protecting your plastic means more than just reporting a stolen wallet or alerting the credit card's fraud department of a lost card or unauthorized purchase that shows up on your statement. Those are both good to do, but let's talk about a few other ways to guard your cards.
First, if you won't be using your card, don't take it with you. The only card that should be in your wallet is the one you use frequently, or plan to use during that errand. Keep all others -- including copies of all your credit card information (account numbers, expiration dates and how to contact the fraud department) -- at home.
Second, be smart with your card. Choose to use a photo I.D. on your credit (and debit) cards -- most banks offer this feature, but you'll need to ask for it if you want it. Never give out your credit card information over the phone, and when you're out and about watch whose hands your card is in. And this should go without saying, but never sign a blank receipt.
Lastly, opt out of all those credit card offers that pile up in your mailbox; these offers are an easy way for fraudulent accounts to be opened in your name.
And always, says the broken record, keep an eye on your credit report for any fraudulent activity. Make it easier by signing up for credit monitoring, which will alert you of anything suspicious.