Hannaford Supermarkets issued credit card security tips due to the recent security breach at their stores. It includes the following tip:
Carefully review your financial institution and credit card statements beginning with December’s statement. Contact your credit card company or issuing bank with concerns about suspicious charges.
The Federal Trade Commission maintains the OnGuard Online site that has a section about Online Shopping.
Likewise, the Federal Citizen Information Center has a page with "Tips for Protecting Yourself When Shopping Online." Tips include: