Choose the room you will be using and empty it out. This helps you know exactly how much space you have to work with and what the dimensions are of the room. This affects your design and decoration options.
Paint the room in a bright color that will appeal to children. Pastels such as blue or green are often appealing to children and can have a calming affect as well.
Lay carpeting down once the painting is finished so the children can read comfortably while sitting on the floor. Carpet also provides traction that can help prevent children from slipping.
Place shelving against the walls that can hold the books for the reading room. The shelves should be the first furniture items moved in because once the books are stored, you'll see how much room you have left for other furniture and supplies. The shelves should be a color that goes well with the walls.
Hang posters for children's books on areas of wall space that are available once the shelves are in place. The visual aids help decorate the room while still fitting the "reading" theme. The sides of the shelves also offer space for decoration.
Add furniture appropriately sized for kids to sit and read. Plastic chairs are useful because of their durability, which is useful in a public library.
Hang other decorations and mobiles from the ceiling to further enhance the environment for the kids.