Pay with plastic.

In the U.S.,credit cards offer the same consumer protection whether shopping online or offline--you are liable only for US $50 if your card is used fraudulently. You can also challenge charges and withhold payment in the event of a dispute with a merchant.

An alternative payment option, particularly for buying from auction sites, is setting up an account with PayPal. You electronically transfer money from your bank account into your PayPal account, then use it to pay merchants.