Speaking of cleaning the rotors prior to new pads: What do you use?
Here is the ultimate way to clean and resurface your rotors, far and above sanding away with coarse papers or Scotchbrite and hurting your damn fingers in the process: Flex-Hone for Rotors, Hone Tools, Flex Hones
I did this a few years ago. I put the hone it a hulking, low speed drill like this (450 rpm):
And had a pal (VFR owner!) run a wire-wheel or similar thing on the tire to rotate the rotor at a nice, even speed, something like 20-30 rpm for the wheel assembly, depending on wire-wheel diameter and drill speed. It's not critical, but that rpm makes for a sweet hone pattern on the rotors:
After doing the "outsides" of the rotors, I removed the wheel and swapped sides (temporarily) and did the "insides" which were now outside.
Here's the result, before and after photos:
This effort totally eliminated a little chatter I had in a set of fairly new and very straight rotors. Light braking pressure is rewarded with the smoothest, most progressive feel you can imagine.
Of course as LDH said, glass-beading is great
if you have it available, but.....it only cleans (perfectly). It doesn't provide that nice hone pattern.
And if you want to do this and NOT replace pads with lots of meat left on them, simply buff the pads on rough, clean concrete for a few seconds (really!) to get a new surface.