Here's the list I go by each trip:
PRE-DEPARTURE
Passport
Emergency Information folded inside the passport & luggage
Student insurance for cameras, etc.
Traveller's Checks ($200 worth)
Credit/Debit cards (one on my person, one hidden in luggage)
Currency
Guide Books/maps
Photocopy all documents (including tickets)
BASICS
Luggage/travel pack
Travel towel, face cloth
Camera/memory cards/batteries
Wet weather gear (rain jacket, rain pants)
Water bottles
Phrase Book
Travel journal
Address book (for postcards)
Travel locks (MUST be TSA-compliant)
Luggage ID tags
Hat
MAINTENANCE ITEMS
LED Flashlight & batteries
1 trashbag liner
More camera batteries
Medication Aspirin/pain reliever
Cold medicine
Diarrhea medicine
Laxative
Sunscreen
Antibiotic cream
Personal hygiene items
Personal prescriptions
TOILETRIES
Comb/brush
Dental Floss
Deodorant Soap - personal & laundry
Trial-size shampoo
Towelettes
Electric razor
CLOTHING
1 pr casual pants
1 pr casual cargo shorts
2 WICKING T-shirts
2 casual (polo) shirts
1 dress shirt
1 pullover
1 lightweight jacket
Boxers
Socks (WICKING)
Bathing suit
2 pr Shoes max (runner, sandal)
Choose clothing that BREATHES, WICKS, washes easily & dries quickly. NO JEANS.
ESSENTIALS
Daypack (In transit it will hold all the valuables you need to keep close: tickets, camera, prescription medication, and reading material. Once there it will be your everyday bag).
First Aid Kit (A compact travel health kit is a must.)
Passport/money carrier (It is essential to keep passport and money secure.)
Travel watch/alarm (Lightweight, water resistant and reliable.)
Electrical converter/adapter
Flashlight
Sunglasses