If you are coming here by car you should ensure that your green card covers Serbia because obtaining a reliable auto insurance is essential.
The Green Card is an international document certifying the issue of automobile insurance against damage caused to third parties abroad.
Some insurers do not provide cover. You need to clarify the situation with you insurer before you arrive, otherwise you could be driving without insurance. After getting adequate car insurance, take along the documents as a proof and photocopy everything and keep the copies with you somewhere safe.
Green cards are issued for the following countries in accordance with agreements signed with national bureau: Andorra, Greece, Spain, Austria, Iceland, Sweden, Belgium, Ireland, Switzerland, Finland, Italy, the Netherlands, France, Luxembourg, Great Britain, Germany, Portugal, Tunisia, Hungary, Cyprus, Romania, Bulgaria, Albania, Croatia, Macedonia, Czech Republic, Poland, Bosnia and Herzegovina, Norway, Latvia, Slovakia, Turkey, Estonia, Moldavia, Denmark and Ukraine. A green card pertaining to a vehicle bearing registration plates from these countries is valid in Serbia only if the symbol for Serbia is not crossed out.
Drivers of cars with foreign number plates who do not have a green card must purchase border automobile insurance from a local insurance company at the border when entering Serbia. The insurance you buy at the borders is valid for accidents caused by you and compensates the other driver's damage.
Here you can find price of border insurance for foreign-registered vehicles, valid from July 1st 2010, payed ONLY in Dinars.