GimpyPorcupine wrote: »Guild traders are your best bet.
I suggest you look here for details.
Note that some furnishings have to be bought, and can't be made, and some of those are only available from the Crown Store. In particular, plants (trees, shrubs, flowers, etc.) can't be made, but a lot can be bought from the Furnisher merchants.
The thing I find most annoying is the rows of books. You can make a few bookcases already containing books, but most styles don't have any, and the books themselves are crown-store-only.