I avoid using my debit card for online purchases. Paypal is handy, but they can be a PITA to deal with for issue resolution. They are easy to use as a payment processor, but I prefer other solutions. I've dealt with building/maintaining online payment portals for almost 15 years. There are lots of ways to do them and lots of ways to screw them up (I've seen CC numbers stored in full as plain text). It's not something you want to screw up. A security audit is painful.