More visible stop light-
Buying a high quality bulb for it, or an all new aftermarket light housing and bulb.
Tap the brake levers several times before stopping.
Wear a bright colored jacket and helmet.
I glued four round red reflectors (the thin type) from a Lowes that I cut from a bigger rectangular reflector, to the upper back of my dark gray jacket, for better visibility at night and in the rain.