What you need: made-for-baby nail trimmers or an emery board
It’s often easiest to tend to your baby’s nails while he’s sleeping so he’s less likely to make any sudden movements. Using a pair of baby nail trimmers (some come with a light or magnifying glass to give you a better view), push back the finger pad by gently sliding the clippers under the nail. Cut along the curve for fingernails and straight across for toenails. If you nick baby’s skin, don’t panic. Apply light pressure if the cut is bleeding and clean it with peroxide before putting on a bandage to prevent infection.
My preferred method was to avoid clippers altogether and simply file my baby’s nails down with an emery board, which works just as well for the first few months (and is much less terrifying!).