Draw the head shape first
Mark the hairline
Sketch the main hair volume
Add the parting if needed
Outline the outer silhouette of the hair
Draw large clumps or sections
Add smaller strands within the clumps
Follow the direction of hair growth
Vary the line thickness
Add shadows where hair overlaps
Darken the roots and inner areas
Keep the tips lighter and looser
Refine the shape and clean the sketch