NOTE: If you are not fond of or can't kill, then this is not for you it does involve rather a lot of sleeping kills**
1. So to begin with you need to find a place (maybe in Imperial City, though a house anywhere will do fine) where you can store absolutely everything you have (excluding your best weapon and anything that lets you carry more (e.g.: feather pants)) for the remainder of this mission, since you will need to be able to carry a frickin' lot.
IMPORTANT: Enter sneak mode at this point and remain in it for the rest of the mission.
2. Next you need to be near the North Watch Tower (market district) in the Imperial City at around 1am. Enter the tower (there shouldn't be anyone in the first room), proceed to the second floor and kill all the guards in the room. With luck there will only be sleeping people in there, so easily dispatched. Take all the armour and weapons they have.
3. Head up to the barracks via the ladder and there will very likely be five guards sleeping, if there is a guard standing, kill him quickly and take all his armour and weapons, like you did with the last guy.
4. Now the beautiful part! Each guard sleeping in this room has an ENTIRE inventory of full set Imperial Amour, and either a fine iron bow or steel longsword. Now creep around the room (starting with the guard on your right) slaying each one in their sleep. You should kill each one instantly because of the sneak attack bonus. Now take their stuff and head to The Best Defence store in the Market District (very close) and sell it for a very decent and profitable profit! If you can't carry all of it simply leave it behind and fetch later. Don't worry about the selling stolen goods barrier; The Best Defence (or any other shop) will still buy because if you kill the guards before taking their stuff it is not stealing in the eyes of the game. You may also want to keep some for yourself, it's pretty handy!
So there you are, I hope this helped and please give your opinion in the poll. Happy thieving!
Dawn
**"cowardly?" I prefer "better safe than sorry"
UPDATE: I'm very sorry if you are an experienced player who has taken his sweet time to read this; this is for people who aren't very experienced and need easy money.