Ditch Your Reflectors For Reflective Tape
Instead of using those unsightly reflectors that shops are required to put on the bikes they sell, get yourself some silver reflective tape.
It's light, looks good, and doesn't get in the way when truing wheels.
I like to put it on my seatpost, seatstays, spokes, and especially crankarms and pedals.
Cranks and pedals are great because they are spinning, and that makes it easier for cars to notice you.
The brand pictured is stuff from 3M. I got mine on eBay since I was having a hard time finding silver. (Yellow is easy to find in most stores, but it doesn't match most paint jobs.)
(Note: If you aren't worried about style points, feel free to use all the reflectors you can fit on your bike.)