Ride with, not against, traffic. Always wear your helmet, gloves, eye protection and use your mirror. Think visibility whenever you select your daily riding attire. Permanently mount a flasher to your bike and use it in shaded areas, tunnels, on cloudy days and at dawn and dusk. In fact, we have started using them almost all the time.
Batteries are cheap.
Stay as far to the right as road surfaces, parked cars, and traffic conditions allow. Watch for doors opening from parked cars. Generally ride a door length away from parked cars. Make eye contact with other drivers to ensure each of you knows the other's intentions - to turn, yield, stop, etc. Avoid pacelines and drafting unless you and the other riders know exactly what to do and are prepared to do it.