Step 1: Sketch out the base of a head.
Step 2: Add a hair line to the head.
Step 3: Around the head draw a big circle this will be used a guide for the afro.
Step 4: Using the hairline from step 2 as a guide. Make the hair line more bumpy and curly.
Step 5: Using the circle from step 3 as a guide, make hair lumpy and erase any lines that cover the face portion of the head.