If you want to fill some of the empty expanse of wall on your staircase, consider hanging some pictures. Hanging a picture on a staircase is really not different from hanging it in any other part of your home, but the slant of the staircase may cause you to accidentally hang the photo crookedly. You must not trust your own perception when hanging the image over the stairs so you can maintain a level picture frame.
Run a stud detector over the wall on the staircase. Gently mark the studs on the staircase wall with a pencil so you can remember where they are. The wall on the staircase vibrates when someone walks up and down, so it is imperative that you hang your frame on a stud.
Stand on the stairs to properly gauge the correct height at which the frame should hang. The location should be at eye or shoulder level up the wall so that you do not have to strain your eyes up or down to enjoy the photo.
Mark a small "X" on the wall with a pencil at the height of the top of the frame. This will work as a reference for where you should insert the anchor for the picture frame. Ensure that this mark rests over one of the wall studs.
Hammer a nail into the stud. Leave about 3 mm (1/8 inch) between the head of the nail and the wall to allow the nail to catch the picture frame and hold it up. Place the picture frame over the nails and move it around until it catches.
Hold a level up to the wall just above the picture frame. Move the frame and the level around until the bubble of air centres in the liquid chamber. This means that the level is sitting at a straight angle across the wall, which means the picture frame is straight.
Hang multiple picture frames at a slant instead of all in a straight line. It creates a more visually pleasing effect and makes it easier to see all of the images as you walk up and down the stairs.
Use an adhesive hook to anchor the image to the wall if you prefer not to drive any nails into the drywall.
Always use a level when hanging an image on the stairway. When you stand on the stairs, your perception might be at a slight slant, which results in a crooked photo. The level's perception will always be correct, though.