streetsmart shopper is vulnerable to fraud and financial mishap. But according to Michael Greenfield, law professor at Washington University, there are a number of ways one can avoid getting socked financially: Budget your purchases to avoid finance charges on your credit card account.

Pay balances off each month if you can. Mr. Greenfield estimates an annual finance charge of $500 on a $2,000 balance for some card plans. "If you need to carry a balance, pay it off quickly. Never pay just the minimum.'' Watch out for telemarketers. Beware of alleged "surveys'' that turn into sales pitches. Never give out your credit card number unless you are the one placing the call. "You could be talking to someone who is after your card number, not your business.'' Keep track of credit card receipts and carbons so that no one can pick up your account numbers. If someone does get your account number, you are only liable for the first $50 of fraudulent use, but it's a big hassle getting fraudulent charges removed. Check your credit card receipts against your bill.

Check your credit card statements for erroneous charges as soon as they arrive. Errors can be made or they can point to fraudulent use by someone else.