Unite your shelf displays by grouping item by color, shape and texture.
Use books stacked for boosting an item's or other riser like a wood box or a cake stand. Arrange books by color. Display some books up and some down on their side. Also display books by size instantly creates a sense of order. Try removing the dust jackets on your hardbacks. Mix art with books. I love framed art placed casually among books.
Show off your collection
Anything looks better as a collection. The different sizes, shapes and colors play off each other, and grouping a collection together gives it emphasis.
Display object in odd number
Place several objects of similar shape, size and color together in odd numbers for maximum impact. Groups of three or five work particularly well and are stronger visually than a group or two or four.