Is it a better idea to set up GIRO for credit card payments? Or manually make payment each month?

No, I don’t do GIRO for credit card payments. I always double-check my transactions before paying up. And by paying manually, it allows me to know how much I really spent. I find this way it’s better than just letting GIRO deduct the amount coz sooner or later you won’t be bothered of how much you spent.

I set several reminders for the due date and have a habit of paying early so late payment is not an issue.

I GIRO all my cards so yes if you're not careful, your bank balance may be too low and the GIRO won't go through, resulting in late charges (it's usually first or second time you can apply for a waiver).

But I do still go through my statements every month before the due date as a discipline, so I know where my money is going and it also prevents the GIRO from failing since I am prepared for the bill.