I think Debit cards are fine if you plan on using them for something either necessary or worthwhile. If your fridge broke, for instance, and you desperately needed a new one - putting it on credit is a good idea. Or if you need to make a necessary, long-term purchase, the flexibility to pay it off over time is great.
Sometimes at work, I see people buying food with credit cards. This shouldn't become a habbit as paying interest on food that you cannot afford to pay up-front is a bit crazy.
I think taking out an interest-free (or low-interest rate) credit card is a good idea as it contributes to your credit history/score. A good idea is automating bills to come out your credit card and putting the cash back into the card account straight away. This builds you a good credit score while making the most of rewards like frequent flyers. :)
I agree, I am also enjoying the rewards by using my card frequently.