Bring your passport with you and keep it in a safe place while you travel. You will not be able to return to the United States without it. Also pack any required visas. Consider bringing a photocopy of your passport and visa documentation as well, to store in a separate place in case you lose your passport.
Pack all prescription medications in their original packaging. Bring enough to last you for the duration of your trip and a few additional days, along with a copy of the prescription from your doctor and a note from the physician if the prescription contains narcotics or another controlled substance.
Pack a first aid kit for illnesses or injury that may arise when you travel. Depending on your destination, you may want to include antimalarial drugs, altitude sickness drugs, and antidiarrheal medication. Also include a pain reliever, antihistamines, and cough suppressants for every day colds and flu as well as basic first aid supplies.
Pack your airplane tickets and a copy of your itinerary, especially if you have multiple connecting flights or train connections. Also bring any hotel or other reservation information.
Pack a voltage converter if you are bringing along appliances (cell phone charger, alarm clock, hair dryer) that you plan to plug in and are traveling to a country that does not operate on 110 voltage.
Pack clothing and shoes that are seasonally appropriate for the country you are visiting. Choose shoes that will be comfortable for walking in and clothing that can be layered and worn multiple times for versatility.
Purchase an international calling card to use for calls back home and bring it with you if your cell phone is not equipped to work overseas. Research your cell phone plan's rates for international calls before using it abroad to avoid surprises on your bill.
Pack an extra pair of glasses or contact lenses, if you wear them.
