Minecraft wiki entry for Things_not_to_do, associated text: Milk (optional, to get rid of poison or other negative effects)
Honey Bottles (optional, to get rid of poison specifically, leaving all other status effects still active)
Sword (Iron or better)
Bow and arrow (Useful in caves with lava)
Pickaxe (Iron or better)
Building blocks
Bucket of water
Shears to cut cobwebs
Armor (Full Iron or better)