In the USA, we typically only need to enter PIN (personal identification numbers) on debit cards not credit cards. In many parts of the world, you need PIN numbers for both types of cards. You may want to call ahead to your credit card companies before you travel to see if you can set up a PIN.
As noted in a previous tip, it is also helpful to alert your bank of your travel plans. Many have an online form you can complete to set that travel alert.