Paint the bookshelf with blue paint. Use one color for the entire bookshelf or use one color for the sides and shelves and another for the backing for a dual-toned effect.
Line the shelves with blue fabric to help eliminate dust build-up. Choose a solid blue or a pattern of blue and white or another neutral color.
Arrange blue flowers into blue glass vases and position these on top of the bookshelf or between the shelves. Use fake flowers so you don't need to worry about water dripping onto the bookshelf or keeping the flowers alive.
Paint a pair of bookends blue to accent the shelves on which you keep your books.
Select knick-knacks that are either completely blue or feature the color blue. Arrange these knick-knacks on the shelves among the books. Use heavier knick-knacks in place of bookends.
Place blue candles, or white candles in blue candle holders, or a small blue lamp onto shelves on which you want a little light. If you have books or other flammable materials on the shelf, use a lamp instead of a candles or refrain from lighting the candles.