Cold and dark.
iz commented about the dark. Dark when we leave home, dark when returning. How do people handle it?
I alter my route to one even less traveled by cars. I assume that cars will not see me and ride in a way that they don't necessarily need to see me. Occasionally I ride on the sidewalk for short spells, especially if I am in a low night-time pedestrian area.
As for lights, since the city is already moderately well lit, the lights on my bike serve to alert, not brighten my way. Both front and rear lights are made by Blackburn. Both have a flashing mode, among others. The front light's steady-on mode is an excellent flashlight, a great asset if something goes wrong (also good when touring, instead of bringing one more thing).
My bike has reflectors all around, improving my visibility from the side, and I wear a pants tie down, which has reflective tape as well. Adhesive reflective tape can be purchased from car parts stores and sew or iron on tape can be purchased online from BikerHiway at a very reasonable price. You can even cut the stuff into cool shapes.