well I am new to caching but an old hand in the bush.... carry a good knife and keep it sharp.
Many other suggestions were great... I have been carrying an engineering compass in the bush for some time... good for taking a heading.
I have a new style zenon(sp?) flashlight that takes 3 AA batteries... 1 more of the same kind my gps takes, and those new style flashlights put very little drain on the batt's ...should ya need to switch.
I also carry a hunk of pine sap for starting a fire if need be.... nothing beats it. Keep it in wax paper in an old sock.