It differs from one brand to another. For Shell:
1. Insert bonuslink card (refer to the diagram at the pump)
2. Remove bonuslink card when prompt.
3. Insert credit card. There will be some display at the screen to verify the card.
4. Remove credit card when prompt.
5. Pump.
6. Place pump at its holder, take out receipt.

Step by Step:
i) 1st insert your petrol card into the card Slot at the pump & remove the card after the instruction...
ii) Insert  the Credit Card in the slot & wait for transaction (process)  approval
iii) After approve (there was dime Green Light near the Card slot) Your can retreat yr Credit Card now
iv) Take up the Nozzle & start petrol filling for your Car
& after finish it put the Nozzle back wait for receipt Printing after keep it for your record

Note: Petrol Transaction at the Plumb (outdoor)
Pre-authorisation amount (usually $200) will be charged to customer's card account during the fill-up.The Pre-authorisation amount will be reversed back & the actual filled-up amount will be charged to customer's bank account(card) once the bank receives the actual  filled-up amount from the acquiring bank. Average pre-authorisation holding days is 3-5 days

The bank don't make profit from you at all, really they don't if you pay in full.

Here's how the bank will make money -
1. Every single transactions swipe with the merchant - small percentage goes to the bank, ranges from 2%-3%.
2. Interest from rollover balances - if you don't pay in full.
3. Misc Fees - Annual Fees but these days it's waived anyway, Card Replacement Fees but this is rare, etc. (Very minor contribution if there's any)

It's the No.1 followed by No.2. So, are you fully satisfied and completely convinced (and your sister) that the bank doesn't make money from you if you pay in full ?

CAN... you can do it so with Debit Card, depend the Spending Limit that You set on the Debit Card (Usually 5 k per day... but some Debit Card with 10 k Spending Limit). Actually You Set Any Spending Limit on Debit Card