Lots of really great advice here. Thanks all. I'm going to start by ordering a brighter headlight, backup taillight, and a reflective jacket. I think I'll also add a helmet light. Once I have those, I'll do some test rides around the neighborhood. In the meantime, I can almost always arrange to leave work so that I get home before dark.
My last real hurdle is mostly psychological. Even if I'm well equipped and feel comfortable with my night-time riding skills, I still have to contend with the fear that my bike will break down on the way home, leaving me pretty vulnerable on the side of the road. I live in a high-crime city, though my route doesn't take me through any "bad" areas. I'm going to start scouting out a route that would keep me in more public areas than my daylight route does. That would put me in more traffic (but still not heavy traffic), but the trade-off might be worth it, especially if bikes are more visible at night than during the day.