This worked perfectly for me:
CHANGE-THE-FULL_URL.com?firstName=[[contact.first_name]]&lastName=[[contact.last_name]]&zipCode=[[contact.address1.postal_code]]&country=[[contact.address1.country]]&phoneNumber=[[contact.phone1.number]]&addressLine1=[[contact.address1.line1]]&city=[[contact.address1.locality]]&state=[[contact.address1.region]]&emailAddress=[[contact.email1.address]]&promoCode=PROMOCODE
Based on this:
