All other nationalities need a visa. Entry to nationals of FYR Macedonia will be denied. Citizens of the CIS, China, Cuba, North Korea and Vietnam must register with the police within 48 hours of arrival. Travellers Cheques are useful in the cities but not in the rural areas. Cash is necessary there.
Cash gets a better rate.
All post offices have exchange facilities, often offering better rates. Major credit cards are accepted, but generally only in the more up-market establishments. ATMs accepting credit cards are present in the bigger cities. Health Vaccination against yellow fever is required when arriving from an infected area and over 6 months of age. Terrorist activity has occurred on the Greek mainland in the past, including bomb blasts, but shouldn't be of much concern to the traveller.