In pink or clear nails, you should be able to see the vein or "quick" in the nail. Don't cut down to that or you baby will be bleeding. It's a lot harder to judge how much to cut on black nails because you can't see the quick. At first, I always managed to make Riley bleed (and what a mess!!!). I just started cutting a small bit at a time and doing it more often and I don't make her bleed anymore.