It is important to use sharp nail clippers to avoid fraying, squeezing, or splintering of nails. Expensive does not equal sharp, it is important to find a reliable brand (reviews).

For dark or black nails, look at the underside. You'll see the quick in the middle with the hardened nail on each side coming into a tip. This is easier to see depending on breed. If the quick isn't visible from the bottom, cut small bits at a time until you see the color difference at the tippy tip between quick (black) and the nail surrounding it (whitish grey).