Originally Posted by stephen122333:
“Buy an iTunes card from a huge range of high street shops (including. Argos, whsmiths, clintons).
Once you have brought the iTunes card, you log into your iTunes account click redeem and the credit is added to your account.”
Agreed. The most secure (though not the most convenient for most people) is to buy an iTunes gift card in a high street store using cash, as there is absolutely no risk of anyone getting into your bank account, well, unless they watched you putting your PIN into a cashpoint and stole your card

From time to time certain stores even have offers where you can get a discount on the gift cards meaning you get more for your money than usual.
In this day and age, paying online is the way forwards, and I have no problem doing so (and have never had any problem with it either at any of the many online stores I've used over more than ten years).