A clean lampshades makes a bigger difference than you'd think. Here's the most effective method, plus the mistakes most people make.
Use a lint roller or soft brush to remove surface dust. For pleated shades, work a clean paintbrush into each fold.
Gently vacuum the shade with the soft brush attachment to remove embedded dust.
Dampen a cloth with Vibes Multi-Surface Cleaner and gently blot stains. Test in a hidden area first.
For washable fabric shades, fill a bathtub with warm water and a small amount of detergent. Submerge and swish gently. Rinse and air dry.