Attic Rat,
With 14/2 and 12/2 UF, if you're looking at the end of the cable, you'll see the ground wire
favors one flat side or the other. I skin about a 1/2 inch off, then I pull the ground wire with the linemans pliers. Once I pull back the ground, one at a time, I then pull back the black and white, to what I need in length.
Hope that helps