first off, always go into dungeons leaving all your un neaded equip on shadowmere who i assum everyone playing the game has. you wnat to be able to carry as much loot as posible. secondly, always empty every container unless your almost over encumbered, loot in dungeons respawns after a while but only if youve cleaned it out.(monsters loot dosnt count), finally, i recomend you, dont wear dadric armour unless your a expert in heavy armor, or any other heavy armor. it takes alot of weight. you may think im over parinoid about being over encumbered but seriously, nothing sucks more then killing that last bandit ringleader, seeing he has awsome echanted dadric, then haveing to drop half your loot so you can carrie it. enoph said, here are the best locations to raid for loot.
ROBBER GLEN~Robber Glen is just north of Bravil. Just follow the road north for a short while it is off the road to the right
ROCKMILK CAVE~This is located right across the Niben bay from Fisherman's Rock.
CRAWFISH CAVE~
FORT WOODENHAND~