While some people now do the majority of their shopping online, others are still hesitant to trust the Internet with their financial information. My Dad would fall into the latter category, but he recently asked me about opening a credit account to shop online. I sent him a message that turned into a rather lengthy tutorial about safe shopping online. I have modified the text of that message and posted it here, in addition to links to the sites I mentioned. I have personally purchased items from the retailers listed, and would recommend them to others.
The easiest way to keep the majority of your income safe would probably be to open a checking account with your bank that you will use exclusively for online transactions. This is not absolute fraud protection, but it will mitigate the amount of damage incurred by things like credit card theft.