Books alone can look messy and visually boring.
To make shorter items more appealing, stack books underneath them for height. Choose colors that will coordinate with each other, and the books if possible . Use tall picture frames or small paintings for higher vertical lines. If matching items are used, such as a pair of vases, put them on the same shelf with one directly on it, and the other with a book or two underneath. Use paperbacks to stack items or store them behind other books.