Draw three long, slightly curved strands side by side
Cross the left strand over the middle strand
Cross the right strand over the new middle strand
Repeat alternating left and right crossings down the length
Keep each strand slightly tapered as it goes down
Add small overlapping curves where the strands weave
Vary the strand thickness for a natural look
Draw a loose outline around the braid if needed
Add a few flyaway hairs around the edges
Shade under each overlap to show depth