I think Oscar brings up some great points. You may think that you are shopping with reputable vendors, but you are dramatically increasing your risk when you shop with sole proprietors versus large national corporations.

You might want to consider having two seperate credit cards: one for only essential budget items like your electric bill, phone, internet, etc. and another for other fun online purchases. That way you will shield your very important card as much as possible.

The more you use your card online the more likely you will run into this problem. While most sites have security in place that rivals NASA, some are horribly horrible. I'd suggest shopping at sites that you know are reputable, and I'd suggest using merchants who have secure servers.

The good news is that you have pretty much no liability for fraudulent use of your credit cards, so it's just irritation.

That's the downside of using cards online and nobody has figured out how to prevent abuse 100%

Shopping online offers many unique opportunities and challenges.
Security should rightfully be of paramount concern, ...but don't be paranoid.

First- shop with reputable vendors.

Second-make sure the site is secure. In the address window after you've logged in should appear https://
the s means it's secure.

Third- Consider your history, you may want to use a service like paypal for security. You establish an account with them, deposit funds and use their service to safely pay vendors. A debit card is also available with cash rewards for credit charges.

Good luck and be safe.