Use your thumbnail to start a split at the narrow end of the branch. Pull the halves apart; then put your two thumbs between the split. Place your fingers on opposite sides of the branch and place even pressure against your thumbs as you split the willow branch down it's length. The two halves should curl away from each other in a 'Y'.
If one half starts to split thinner than the other, bend the thicker opposite side of the 'Y' more firmly, re-centering the split.
