1.)   Getting into the Mansion

Head to the E, wait in a shadow that the Servant passes by (you don't want him to remember your face, do you?), and grab the arrows from the niche.

Head to the N, and enter the sewers through the first metal sewer-gate that you see. Find the room with the switch, pull it, and head to the N. Climb the (sometimes tricky) ladder, and come back to the streets in the back of the drunk Guard. Snatch the key (pickpocket: 1 of 4), enter the well-house, lock the door from the inside, and hop in.

In the room with the water dropping from the ceiling, you want to dive and to find the entrance to the Spider-cave. Leave the water in the corner opposite of the Spiders, so that they are (not yet) alerted. Spiders are not able to tell anyone who stole the ring, so just run to the chest, and jump back into the water.

Follow the water-way and enter the basement of Lord Bafford's Mansion.

2.)   Getting into the 2nd floor

While you grab the healing potion from the chest, you will hear the conversation of the two Guards. Wait until they have finished their faszinating intelligent dialogue, and follow the one who heads ahead. If you want the two flashbombs from the chest, you might want to run past him.
If you were too slow but want the two flashbombs, you want to douze the torch in the storage room in his back, then throw some junk on the metal floor tiles, hurry to the douzed torch, and wait that he will search for you on the metal. As soon as he has his back turned, you can run to the chest, grab the flashbombs, and run to the stairs.
Or you were too slow, but don't bother because you don't have a need for these flashbombs anyway. Then just keep very close to the left wall, and sneak to the stairs, as soon as he has reached his idiling position.

The small amount of loot in the chest that is leaned against the wall, not in the left one.

Now you want to grab the Vase from the kitchen. Hurry past the room with the sleeping Servant, head W, and a few steps N, open the door, and get the Vase without ever getting seen.

Head back to the stairs. It is now your choice if you don't bother that the drunk Guard in the N may rememer having seen you, or if you want to sneak through the S. However, reach the shadows in the center of the halls N or S of the pool.

Time your movement with the patrol pattern of the Guard in these hallways, and grab all the loot from the rooms in this area and in the towers with the stairs. Then head to the 2nd floor, and the most favourable way to do this is the tower in the SW.

3.)   Getting the loot from Lord Bafford's private rooms

Watch the patrol pattern of the Guard in the hallway ahead of you. Wait until he either heads to the W or into the garden, and run to the door in the E. Snatch the ring, and open the door that leads to the area with the three Sergeants. Make sure that you move silently over the noisy floor tiles to the carpet, and head to the shadow just N of the door to the dining room NE of you. That shadow is the perfect place to grab the 2 keys from the Sergeants (pickpockets 3 of 4).

When you have the keys, enter the dining room. The Sergeants will react to a changed position of the doors to the dining room and to the bedroom, so enter and leave the room when there is none of the two around.

As soon as you are back in your shadow N of the door to dining room, you may either want to head to the 'secret' room in the basement now, or to the throne-room. I prefer the 'secret room' now, without any special reason. So, wait until one of the Sergeants has passed by, and then follow him. Be slow and careful when you sneak from your shadow to the carpet, but you can be as fast as you want once on the carpet - as soon as you are in the entrance area of the bath, though, you want to move slowly and silently again. Head into the bath now. If your timing was right, no one will see or hear you.

Cross the bathroom, and head to the W. The perfect way to do so, is to sneak in a counter-clockwise direction around the bathtube - so the Sergeants will never catch a sight of you if you are doing it right. You don't even need to douze any of the torches.

Once you are in the W of the bath, you should wait behind the N wall that the Sergeant passed by. As soon as you see his back, you can sneak over the corridor into the hallway ahead of you. Follow this hallway to the 'secret' room, read the book, grab the key and the wine, and head back to the bath. Repeat the same procedure as how you went to the 'secret' room, and as soon as you are in the E of the bath, S of the entrance, you should wait for a good moment to pass the hallway and head to the throne-room. (Because I don't like to slash tapestries, I don't enter the throne-room through the secret passage, usually. Feel free to enter it as you wish.) Unlock the door in the S, and go in.

You are now in a couple of rooms with a Sergeant and 7 torches. You want to douze all of the torches, and then get the last pickpocket and the sceptre.

Always stay in the shadows, and shoot the torches that you can see (or see by leaning left and right) with your water arrows. The 4 torches in the first room shouldn't be a problem.

The 3 torches in the room with the throne, though, are a problem. You can douze two of them by sitting on the very end of the rectangualar carpets, and by shooting a water arrow at the wall next to the pillars inside of the room with the throne. Experiment around for a while (feel free to hit the F11 and the F12 quite a few times here until you got the trick), and after you've douzed these two torches, you can approach the Sergeant and the last torch.

As soon as you are close enough, you may want to snatch the key (pickpockets 4 of 4).

You should now be close to the E wall of the hall infront of the throne. If you wiggle around a bit, you can make out the last of the torches: Inside of the throne room, and just above then entrance. Wait that the Sergeant does not look into your direction, and then pull out your bow, and try to shoot the water arrow at the torch or at the wall as close to the torch as you can get. This will usually alert the Sergeant a bit.

Ignore his question "what was that?", and sneak slowly into the throne room. If you bump into the Sergeant, he will not be alerted - just make sure that you don't make any loud footsteps.

Grab the sceptre, and leave in the same manner as you entered.

Don't be scared too much when the Sergeant will say his "must have been nothing" when you have reached the safety of the carpets again. ;-)

Hurry to the door in the S, wait that the Sergeant outside has passed by, leave and lock the throne room again.

Now there is not much left to do no more. Head to the bedroom, and to the library, and take what you find.

4.)   Getting the last two pieces of loot

At this time, you should have already as good as all the loot. If you followed this walkthrough step by step, though, then you are missing now the 2 silver coin stacks from the rooms in the W of the 2nd floor.

Leave the library, and head to the shadow just ahead of you. Wait that the Guard walks into the tower, and run to the W.

In the shadows just E of the 2 rooms, you are in the perfect place to listen to the footsteps of the Guards on these small balconies to the entrance hall. The Swordguards will enter the carpeted rooms here and then - as soon as you hear that they are moving over the stone surface of the balcony again, you should count up to six, and run to the stairs in the rooms. Grab what you came for.

5.)   Getting out of the Mansion in the most stylish fashion

You are supposed now to leave the Mansion. The front entrance may be quite a challenge as a way out, but you are supposed to take the exit in the N. You can now either sneak back to the N of the 1rst floor, or take the way over the roof.

You enter the roof of Bafford's Manor from the railings in the garden (with a run+jump). Turn the brightness of your monitor to a reasonable level, and explore the roof.

Leaving it without taking any damages is possible either in the S (hop on the lantern opposite of the well-house, and find yourself back in the starting area), or in the N (hop down to the northern exit, pull the switch, and leave through the exit you were supposed to go through.)