By Mike Dunn

PHILADELPHIA (CBS) — The arrival of Thanksgiving means, of course, the arrival of holiday shopping.  And that means scam artists will be out in full force, in person and online.

Today, Philadelphia’s district attorney had some warnings.

DA Seth Williams usually does his holiday shopping warning announcement one day before Thanksgiving.  But this year he did it two days before, because so many stores will be open on Thanksgiving Day.

Among the new scams, Williams says, is online companies selling used gift cards.

“Look up reviews for any third-party seller offering used gift cards for sale,” Williams advises.  “The FBI warns that cards reported as stolen can later be disabled, leaving you with a worthless piece of plastic.”

And beware of Black Friday e-mails.

“If you receive an unsolicited Black Friday e-mail, don’t click the links,” Williams warns.  “And don’t give them your credit card number.  It’s most likely part of a phishing scam.”

Williams also has the traditional warnings about real-life scam artists, particularly those who approach shoppers in mall or shopping center parking lots with a good deal on a new iPad or other hot product.

“Some crooks are so sophisticated, they figured out how to rewrap packages in plastic.  So what looks like an unopened iPad is actually a box with some notepads inside just to weight it down.”

Speaking of plastic, Williams cautions against using debit cards, particularly online, at restaurants or for big-ticket items.  Credit cards, he says, lessen your liability if something goes wrong, and give you more protections.

The DA’s office issued an extensive press release outlining more potential scams to watch out for.   READ IT HERE (.pdf format)