You can reach the first floor [Eastwick's Grand House - Second Floor] in many different ways - by taking the main stairs, the door on the balcony or the tunnel from the scaffolding. Personally, I recommend that you go for the last variant, because you will then reach a dim corner in the bedroom, with the Architect's wife and the female servant, and you will be able to clear the place of the loot without any problems. Take the Candlestick - 15G and break into the safe on the left. Inside the safe, there are a Necklace - 50G and a Jeweled Egg - 100G. Finally, consider robbing the Architect's wife of her two Earrings - 2x20G, but you first need to make sure that you are standing in the shadows, before you rob her.
After you have explored the bedroom, I recommend that you walk into the bathroom that neighbors the bedroom. In here, you can find a Hairbrush - 4G and a Perfume Bottle - 25G. Now, ransack the Southern part of the first floor to collect an Ink Bottle - 3G from one of the tables. I also recommend that you examine the stairs to the attic (they are next to the exit door). Unfortunately, you cannot reach the Architect's staying place this way but, behind the guard's back, you will find a painting (The Court of Montonessi - The Abundance of Emptiness), which you can remove, using the razor. Perform this action while keeping all precautions, thanks to which the guard will not be alarmed.