Be seen:
- Front "see" light, front blinkie (any bright one) on bike, rear (ditto) on bike, rear (lightweight) on helmet
- Reflectors on bike, wheels, pedals
- Reflective vest

See:
- Many options. Look in the Electronics forum. Tradeoff between weight, convenience, cost, brightness, battery life. Think of how long your commute is (time), how well lit the roads are.
- Fenix L2CD or P3CD make fine helmet lights (bright flashlights).
- I use a front Cateye E500 (I think) and a Fenix L2CD on the helmet. This is enough for bike paths and poorly lit roads. Would not be enough at high speeds or off-road. The flashlight is brighter than the Cateye light but the battery life is shorter (2h. cf 10h.)
- I've gone off my bottle-battery halogens (10W + 10W) due to the weight and inconvenience taking it off and on the bike. I might add a second helmet light to bump up the illumination.