I have flashers front and rear going any time that I'm near dusk.  Once the sun is completely down, I make sure to have my helmet light as well, a [NitRider MiNewt][1]:

[![NiteRider MiNewt Mini USB][2]][3]

The little thing is super bright, enough to light the road for 30 meters ahead, has enough battery power for a few hours, and it charges from a mini USB cable.


  [1]: http://www.niterider.com/prod_minmini150usb.shtml
  [2]: https://i.sstatic.net/Dcbea.jpg
  [3]: http://www.niterider.com/prod_minmini150usb.shtml