Make sure your passport is valid for your re-entry to the U.S. and-- if you are applying for a visa--at least six months into the future. Make copies of the biography page of your passport and your travel itinerary and leave copies with a family member. Follow this link to create your own Emergency Plan and Contact Tree.
If you plan to apply for a visa or visas while abroad, bring extra passport photos for your travels.
While abroad you may need to assign a power of attorney for endorsing loan checks or other important legal matters.
The following documents will need to be either procured or looked into before departure: