i think using a credit card is much more easier and convinient but we should use it with precautions.We should also have some local currency in hand.

That's right, they always used to say be sure you have enough local money in cash to pay for taxi or whatever you take to get from the airport to where you're staying. I'd forgotten about tips -- so you need the right denonimations of money for that.

This really depends on where you're going. I would use a card for well known hotels, travel, stores and services. Never hand your card to someone you don't trust. Cards don't replace the world monetary symbol, the just make it convenient and provide assurances and rewards. It's always good to have local currency when travelling. Plus, most shops and tips can't be paid with credit cards.

A long time ago (when I had more free cash than I have now), I would get foreign currency before I went on a trip. Is it still a good idea to do that, or would you just use credit cards and let them do the exchange? I think that used to be more expensive.