Address Fields on Custom Object

We have a custom object that we have had users fill in the address as an open text field. Now, however, we want to split the address (address 1, address 2, country, postal code, city, state/province) and we want to use the address information from Oracle to validate the address. But when I create custom fields for Postal Code, City, and State, I am not able to get the address information to populate from the Dynamic field choice lists. Is this possible to do? What are best practices for creating address fields on a custom Object?