The only portal I use for my debit card is Lazada, have never had a problem with them. Anyone else, I make a payment to their account. If anyone wants my card details after I have offered to pay that way, I cut them off.
As another poster has recommended, I use a Faraday cage wallet.
On the extremely rare occasions I withdraw cash from an ATM, I will only do it at a bank with a card that matches the bank.
Paranoid, yes. Seems to work for me, I have never been the victim of a card scam.