Use a faux stone painting technique on the walls. Use creams, whites and light beige to create a light and airy castle interior. If you don't feel confident painting a stone effect onto the walls, choose wallpaper with the stone design.
Add a castle window mural to the wall to create the effect of looking out over a magical kingdom or enchanted forest. Drape the "window" with fabric such as tulle, gossamer or shimmera. Attach a hook above the window mural and place a few hooks along the sides. Drape the fabric over them. Use the same fabric to dress the real window in the room.
Purchase a canopy for the bed. Alternatively, create a canopy by hanging a wire gossamer hanger over the bed. Drape sheer fabric over it, so it gently fans out around the head of the bed. Dress the bed with luxurious-looking bedding and add several pillows and cushions.
Paint furniture white to keep the room light and fresh. Place a dressing table in the room and hang an elaborately framed mirror on the wall above. Add a plush, comfy stool to create a grown-up dressing area. This also doubles as a desk for craft activities and homework. Add accessories such as a princess hand-held mirror, vintage perfume bottles filled with colored water and a jewelry box overflowing with fake jewels.
Hang fairy lights around the head of the bed to create soft, bedtime lighting and around the mirror above the dressing table. Use wall sconces for authentic castle lighting and add a chandelier for the main light to add to the luxurious feel of the room.
Introduce any favorite fairy-tale characters in the form of stuffed toys, action figures or pictures. Alternatively, use objects associated with fairy tales, such as a small toy frog, a cuddly stuffed unicorn, a fairy's wand or a glass slipper.