What is a good way to do decorative painting on old windows?

Add decorative paint to old windows by creating a stencil, attaching it to the window and painting it with glass paint in your choice of colors. Lay down some newspaper or old sheets on a solid surface, such as a table, and tape off the areas you don't want painted.

Draw designs on the paper, cut out the designs and tape the paper to the glass. Dip a small paintbrush in the paint, and paint the glass showing through the holes of the stencil. Allow the paint to dry before removing the stencil and placing the window back in its place.