This video might be helpful: https://www.youtube.com/watch?v=XyCGbOepvqQ
Hello Barbara, I have spray painted paper lampshades quite effectively using spray paint. In my last application Inused one color on the outside and white on the inside to have it the best reflective quality.
I would use spray paint!
You can also use a chalk style paint. The trick is to make sure that the lamp shade is slightly damp first by using a spray bottle and then begin painting. :)
I have stenciled on them with plain acrylic craft paint and it looks great and lasted for years.