If I'm not mistaken, most accidents with cars are not from behind. Most accidents are caused by a car pulling out of a side street or parking lot directly into the cyclist. They were looking for on-coming cars or trucks, but not bikes. In those situations I check to see if the driver sees me, (eye contact) and if not, I check traffic to see if there will be an opening in traffic about the same time I will be passing in front of the car. If there is, I'm on full alert and may just slow down and ride behind the car or wave to get their attention.
Early morning fog is another danger spot, That's where reflectors and flashing lights really help. This is also a good time to cycle close to the white line, cars will generally learn toward the center line, which is easier to see for them. A front flasher is also a good idea.
I have a spinning strobe on the top of my helmet along with a purple propeller, OK so I just made that up, but it would be stylish!