Because of differences in electricity, you will not be able to use an American electrical product without an electrical converter and an adapter. These are available at Radio Shack, K-Mart, etc. here in the U.S. or in stores in Greece. The easiest thing to do is wait until you are in Greece and buy an inexpensive hair dryer there. Bring medicines, as described earlier. Bring film and batteries for your camera, at least to last the first week or so.
Film is certainly available in Greece but can be expensive.
Bring an extra towel and a couple of washcloths. Bring a pocket calculator or money converter, if you have trouble converting numbers in your head. These are available in most travel shops and discount centers. Other Packing Suggestions Make sure your luggage is clearly identified. Use name tags and other means of identifying the exterior, such as taping your initials on the suitcase itself.