How to draw hair layers in 1-2 mins

In this case, you only need 3colours.

Step1:

Use the lightest colour to outline the shape and separate the hair zones.

Remeber to sharpen your pencil to make the lines thin.

Step 2:

Fill all basement colour.

Step 3:

Use the darker colour to highlight some area.

Step 4:

Use the black or darkest brown to refine the dark area.

Final:

Use black colour to finish the head colour and some shadow area.

Done