1 big and 1 small backpack
The big one for luggage cabine and the small one one your back (with all the essential survival items just in case you lost your big bag, as it does happen)...
For a short trip of less than 15 days, a small one is more than sufficient.

1 sleeping bag (-10 °C)
A place where you feel at home...you can also find a sleeping bag suitable for tropical weather

1 bag linen
Very useful in tropical countries, where you may prefer to avoid sleeping directly in a suspicious bed.

1 emergency blanket
For emergency use of course, but as well a perfect wind-stopper for a dream under the stars.

3 plastic bags
Not necessary for ecology reason, but rather to be used to separate different items in your bag and to protect them from humidity.

1 swiss army knife
The tool kit which allows to cope with all situations. Do not carry it in your hand
luggage as it may be confiscated at the airport.

1 light scarf
Versatile...especially to keep the dirts off your face.

1 mosquito net
A necessity, it protects you from mosquitos, but as well as rat and other insects...

medical kit + toiletries
Voir the details

3 T-shirt
Why not 4 ? euh ... question of space. Besides, 3 pieces are sufficient for change before you find a place for your laundry

3 underwears
Why not 2 ?! Same explaination as above !

1 polar jacket
Even at equator, it may be very cold at the top of the mountain.!

1 shorts
Easy to wash and can be doubled as a swinwear.

1 swimwear
For the water of course.

1 pants in light cotton
Easier to dry than a jean. Side-pockets are useful as well.

1 long-sleeved shirt
Useful in the evening, a protection from mosquito bits.

1 raincoat
Necessary for tropicl rains.

1 pair of trekking shoes
Useful even in tropical countries

3 pair of socks
Essential to avoid stingy foot, also useful to deter insect bits, especially in desert.

1 pair of sandal
For a walk on the beach, may also be used when you take a shower in unsanitary condition.

Toilete paper
Up to you to decide on the quantity. Note that a roll mesures 33,33 m (in case you need to calculate your consumption.)

1 belt + wallet
This is a belt which can be doubled as a wallet to keep your money inside.Don't forget to put your documents in water proof ziploc.

Documents
Certificate of vaccination (Yellow Fever), Photocopies of flight ticket, passport, Credit card number and other useful numbers, ... All to be kept separately from the original documents of course

1 frontal torch
Ideal for climbing mountains at night

1 lighter, 2 candles
In case of power failure or while camping

1 pair of sunglasses
A basic and cheap pair will do, unless you make sure to take care of your Ray Ban.

Camera
It's your personal choice... Did you see our photo albums and feel inspired?!! ... Pay attention to sand and dirt when you open your lense.

1 anti X-ray bag
In order to protect your films, as not every airport is equiped with the latest X-ray machine...some has micro-wave instead...

Maps + Travel guide
Not always necessary, all depend on the way you travel.

1 GPS
Useful tool for those who travel in 4x4, in desert and in jungle.