@denis The problem with putting the ZIP code first is that there are 58 countries and states with the same five number format, Germany obviously being one of those. So putting in five numbers does not tell you where the customer is (you could use a combination with IP, but especially in the EU for example you will often have customers order from a store in another country, or use a credit card that's registered somewhere else, e.g. Croatia, Finland, France, Italy, also use five numbers).

@tnjh I think country first, then zip/post code would work well in most cases!