I have a virtual card that I run through PayPal, so buyers don't see my actual card number... I've had very good results. I also run a secure browser, strong anti-virus and VPN client. Keeping Apps updated is also very important. Some if not most of those updates are fixing identified security risks and vulnerabilities. I also avoid sketchy sites that either my A-V tells me to run away from, or that just feel weird with lots of pop-ups or crap design.
Just like picking a gas station or store in a unfamiliar city.