Well if you want to just find some good stuff, just go walking along the roads and enter any caves/forts/Ayleid ruins you find. Depending what level you are, there's usually good stuff to be found (the higher your level, the better the loot). There's quite a few Ayleid ruins and forts on the road/s surrounding the Imperial City, and one Ayleid ruin to the South-West with some great armour and one of the best swords in the game. Otherwise you'll usually just find gold, gems, enchanted weapons/armour/ alchemical equipment -- that sort of stuff. Stuff that's useful and has a decent sale value.
Just remember to take lots of lockpicks because you'll almost always come across locked chests and doors. And don't forget to take a silver/daedric weapon in case of ghosts. Oh, and you might want to watch out for vampires in some places. Most of the time it'll just be creatures, zombies, skeletons, easy enemies basically.Here
is a list of locations. Just pick one you're interested in and it'll give you a map and items of interest there.