This tip is for people who get blisters on their heels when they go running, walking or hiking. You can prevent these blisters with a “heel lock” or “lace lock” that creates extra friction between the laces at your ankle. This keeps the ankle and heel area nice and tight, without having to tighten your whole shoe. It also helps to prevent black toenails by keeping your heel and your toes from smashing into the front of your shoe.