well ...
Money
Clothes
lots of Underwear's
Sun screen (If you intend to go to beach)
Condoms (To play safe)
Medicines (allergy and stuff)
A book that contains details about the place you visit
A and extra cash secret wallet .. in case of emergency
A Cellular phone connection ... which you need to use only in case of emergency
Traveler check and debit cards(no credit cards ...because you can get duped)
well a person back home to keep track of your journey
Just a small list