We use the "swiffer" duster which works on the principal of electrostatic
attraction. The napkin sized dusting pads can be purchased in boxes at the
supermarket.
This is good for the "first layer" of dust. After removing the first layer of
dust, using very light to no pressure, we then use a fresh pad of the same
material after lightly spraying the piano with the special polish that Yamaha
sells for their high gloss pianos. They also have a special polish for the
keys. Both are available at Yamaha dealers.