Several surveys have indicated that security is the main concern for online poker players. There are a few things that you could do to make sure that you will remain the only one with access to your credit card details.
Firstly it is really important to choose a reliable poker website. Make sure that you play in a safe environment by reading all the seemingly boring stuff about the used encryption methods, software and collusion. You need to be a bit skeptical about any poker website you are visiting.
Poker websites should also be very clear on their policy with regards to collusion. Secure online casinos make a back-up of all the games played so that you can easily review your hands. There should also be an effective customer services team ready to help you every day.