Paint the ceiling to look like the nighttime sky. Use dark blue or black paint for a realistic look. This provides a stunning backdrop for glow-in-the-dark stars.
Decorate your walls as much or as little as you would like. If you are artistically inclined, consider painting buildings and trees on all of the walls to add dimension to the starry sky you're creating. Or leave the walls as-is so as to highlight the sky.
Place glow-in-the-dark stars on the ceiling. Create replicas of constellations by using the map that came with the stars as a guide. You can find glow stars in toy stores. You can also purchase them online.
Add other glow-in-the-dark stickers to the ceiling, such as planets, moons or comets. These are usually sold in separate packages but can add a lot to the decor. Large stars and planets made of plastic are easy to use, as well.
Place nightlights around the room, as many children don't like being by themselves in the dark. Try to find lights that continue your celestial theme.