I am a newby, but have been adding to my pack as I find a need for new items.
I carry basic items such as snacks, water, map (usually printed from GoogleEarth) ,batteries.
Some items that I have found helpful are :
A Stick to poke around with
Gloves - you never know where you will be sticking your hands!
A dental mirror that I soldered a telescoping handle to.
LED Flashlight
Note Pad & Pen/Pencil
Printed Cache Pages - unless your set up to do paperless caching
Digital Camera - I love vertual Caches and have run into interesting people, places and ideas
Empty Trash bag/s - I pick up as I go down the trail or even in most urban areas I Cache
An assortment of Treasure to place in Caches - I keep a wide assortment, as some Caches really need some exctiement added to them
Compass
If Caching out of an Urban setting I also carryother Hiking basics in my pack.
