Looks like everybody has pretty much weighed in on this topic. I almost prefer riding at night: yes, I'm less visible, and there might be more crazies on the road, but this is offset by significantly fewer cars and arguably, fewer people rushing around to and from work and other business commitments. Riding at night is somewhat liberating too, and perhaps just a bit more thrilling because it is a bit more risky.
And like others, I prefer not to ride at dusk when the sun is setting. Light conditions are changing too fast, in the winter months drivers are rushing home at that time, and things are just unsettled.
That being said, I have both a powerful front light and a blinking back light, reflectors, and preferably, brighter clothing. I've also attached a blinking red LED to my helmet for added visibility. I also try to be more vigilant and not assume a driver can see me. Once, while I was driving, I was startled because a cyclist literally materialized in front of me going the other way. Dark clothes, dark bike, no reflectors, no lights -just a shape moving through the darkness.
I considered more reflective clothing, like a vest, but I often carry a messenger bag or back pack, so it would cover up the vest. I then thought of fixing some reflective markings permanently on my bag, but they would have to be necessarily larger than normal to be effective, and so would ruin the bag's utility in non-cycling situations (think business settings. Also, I don't always cycle with the same bag or pack.
I guess what I need is a large, removable reflector that I can clip onto either me (if I have no bag) or the bag itself.
Suggestions?