The way I always do it, and the way a lot of manuals say, is tighten the nut while hand turning the rotor. If you are using channel locks, go as tight as you can with one hand. If you have a socket and torque wrench available, go about 30 pounds. Now back off the nut 1/4 - 1/2 turn. Re-tighten the nut to 12-16 pounds, or about the dead weight of your hand/arm on a pair of channel locks. I position the handles of the channel locks at 3 o'clock, grip the pliers and just let my whole arm go limp. Adjust for any alignment/retaining pins.