I use cash when I make physical purchases at stores, and debit cards for online purchases. People think they are doing good with credit cards because of the cash back, but sooner or later they will forget or be unable to pay a bill on time, and then they'll end up paying more than what they get back, as well as start getting into debt which will be very hard to get out of. I have two debit cards that give me cash back for purchases, so I can remain debt free and get bonuses!
No, forgetting or unable to pay a bill doesn't happen to everybody, it hasn't happened to me in over 30 years. I check my credit card on line and pay on line directly from my bank account 2 or 3 times a month. I don't just pay the amount necessary to prevent interest charges, I pay the full amount, so I'm always ahead of the game.
I use the Discover card, and I use it for every possible purchase. Right now they have a special deal where you get 5% cash back for gasoline purchases, that gets me at least $10 a month cash back for fuel purchases for 3 months. In September I'll have to pay city taxes for my own rental property and one of my brother's rental properties that I manage. That city accepts the Discover card and the total taxes will be over $2000. Even at 1% cash back, that will add another $20 to my September reward. If I go on vacation, I charge everything, airline tickets, hotels, car rentals, meals, gasoline and all other purchases. I use that card for everything, appliances, electronics, furniture, groceries, I even tried to use it to help pay for cars, but they wouldn't accept a credit card for a car purchase. There have been months (not very many) when I made over $100 on cash back bonuses. Of course it makes it easier if you have a comfortable limit on your card, Discover allows me a limit of $12,700, my Visa allows me a limit of $12,000, but I only use my Visa when there are purchases that don't accept Discover.