I like Michael Smith's decorating philosophy: he doesn't have a signature style. He works with the clients and the location and makes the place livable and comfortable. Unfortunately, to do that you have to have a LOT of money. Not just for the items but for the travel to find the items: London, New York, Los Angeles, Paris, Brussels. You also have to be able to afford custom designed beds & chairs and the time that it takes for everything to come together.
In addition to the interiors themselves, he has a section on his ideas of: the process of design, finding and working with a decorator, buying antiques, the joy of auctions, the virtuoso antique dealer, paint as style enhancer and mood maker, windows, flowers in interiors, appraising a house to buy and staging a house to sell. There's also a list of resources for his favorite choices of antiques, paint, fabric, though some are only "to the trade."
Some of the knickknacks and artwork I love. Others I couldn't stand, especially the gigantic painting in the bedroom and the large tiger hunt painting in the dining room.
I like that he works with the clients to come up with a home for their style and their way of living. Apparently some designers impose their ideas on clients, but he's not one of them. I really like that he doesn't insist on white everything. Walls can have color.
Decorating books are good to help you get ideas of what you like and also of what you don't like.