thats so funny because I just came in from a round of nail clipping.
I use a garden clipper or a wire cutter, what ever is handy. Its easy, hardest part is catching the chickens. Easiest to do in really really good light, so the nail is back lit with the sun or a light. Even with black nails you can get a sense of where the quick is. I've never gotten the quick, so no bleeding, but I am pretty cautious. I would rather clip nails frequently than deal with the bleeding.
I don't have much of a problem in the summer, but in the winter there isn't any hard stuff to scratch, so they tend to get too long.
Today, I noticed one hen has a spur that is growing too close to her leg, it has sort of curled into it. No idea how to cut it without hurting the leg. I've never cut spurs, have heard it is easy to do with a hot potato but that won't work with this because there isn't enough room. Can't believe I missed this!