It really is an art, isn't it? I change mine all the time, and have yet to get it perfect. They keep getting cluttered up when I'm not looking. I think it's because my husband and I have this silent war going on where he keeps adding books and I keep removing them. He wrongly assumes that bookcases should have a lot of books. How silly of him :)
Here are my tips for arranging objects. Color coordinate, and put like items together. So, all red goes together, etc. Candlesticks, for example, should go in groups of three or more, etc. Also, use the opportunity to place items on the shelves that reflect the colors in the room. There is an example below of a room with a red fretwork chair where the items on the shelves tie into the red - great example. Finally, put some items vertically and some horizontally, and never too much on a shelf - don't be afraid of empty space. In my room there is a lot of pattern, and a bold pattern on the rug, so the shelves look too busy for the room when they are packed, although in less busy rooms that would look great. So that's it, the sum total of what I know about arranging shelves!
Here are mine as they are today:
And here are some of my all time favorites:
My other most trusted on-line shops that I highly recommend: