Renewable Energy or Energy Efficiency: Which should come first?

Both!

I think it's much harder to change human behavior than it is to develop new sources of energy, so I'd focus on the latter.  Good luck getting people to turn off lights when they leave a room, buy a smaller car for their family or switch to a more efficient big-screen TV.  The key is to change the source of the energy they're using inefficiently so that producing that energy doesn't kill our planet.