It's understandable to be nervous about using your credit card on the PlayStation Network, especially considering that it was taken down due to hacking just under two years ago. But not to worry, Sony has another option in place that makes it easy for you to make online game purchases without risking your credit information.
The company now offers an option to use your PayPal account to make purchases through the Network. Previously, it was only available in Europe, but Sony was kind enough to bring it over to the U.S. store. The catch, however, is that you need to make the purchases through the Sony account on a website, and can't do it directly through the system. Still, the transfer of funds to your digital wallet is simple enough, after filling out some information.
You can learn more and sign up for the account at the link here.