Cut crisscrossing lines into the skin - the more the better. Just be sure not to cut into the meat. Also, be sure not to cut into your fingers. This video is sped up to satisfy your limited attention spans, Hungry People. No one is that good at scoring duck. Not even us.
Scoring lets the fat render out. It also makes the skin crispy and delicious. Most importantly, it just looks really cool (see photo below).