My standard poodle (huge feet) has all black claws. I use a bright headlamp to inspect after each cut and so I can see what I'm doing. [I also shave all the hair off his feet and toes first.] There is a texture/color change on the soft part of the inner nail/toe tissue when you don't want to go any further. It takes some practice, but once you know what you're looking at, it's easy to get it right. As long as your dog doesn't wiggle too much and mess things up. [My boy doesn't, of course, because he's awesome

and wants his cheese]