Inexpensive ivory soap is good for practice.
If you don’t mind these letters showing a little on your design or on the back of your carving, you can skip this step.
Try using the knife as you would when peeling a potato, keeping it between your finger and thumb and pulling it forward through the soap.
Since the face and upper body are enlarged, you have more of an opportunity to emphasize a character through precise details, such as lines for the hair, lips, and clothing.