Remove dust and small debris from the shades with a feather duster. Fill a bucket with a mixture of soap and warm water. Use a sponge to wash the shades. Allow them to dry and then remove them from the windows.
Put cardboard down in your work space and set the shades down on top of the cardboard. Avoid painting in direct sunlight.
Paint the shades. A good-quality interior flat latex paint will do the job. If you are painting single color, cut in the edges with a brush and then paint the majority of the shade with a roller. If you have chosen a more creative approach, several other techniques are available. Outline the basic design with a paintbrush or a pencil. Paint the primary background color with a roller or a sponge. Dip the sponge into the paint tray and apply it to the shade. Rotate the sponge as you apply the paint to achieve a faux or swirling affect. Once the background is painted, fill in the other details with sponges and paintbrushes. Allow the shades to dry.
Place the shades back in the windows.