At all costs:
Machete.

Followed up by:

Poncho,
Hammock,
50-100' of cordage. 550 cord for pref.
Bungee cords, min of 4.
Mozzie-net,
Mozzie head net, has all sorts of uses.
A very good fire lighting kit,
Water bottles,
Tin or cup to boil water in.
Anti-malarial tablets,
Dry bag with a set of dry clothing in it.
Puri-tabs,
First aid kit.
File or stone to sharpen machete,
Compass x 2,
Mulitool.
Head torch.
Whistle,
Signal mirror.
Food(dried) for a couple of days.

If you are near water add a small fishing kit.

All of this will go in a 20-30L daysack. It looks like a lot of kit, but it is not.

What ever you do: Don't go off the beaten track without this kit. Your courting death if you do.

Other Advice: Google Ray Mears, Simon Hawke and Les Stroud. Watch them through. Lot of infomation re do's and don'ts.