I Usually brush loose dust off first using a very soft paint brush.
Then follow up with a lightly dampened sponge.
:grim: I stress lightly dampened sponge :grim:
and go in a circular pattern following the shape of the woofer.
Be careful near the dust cones as not to push them in , but they can always
use a cleaning as well. cotton balls or cotton swabs are a safe bet for those.