zealous delta
what i see from the references, the hat should be align with the front hair line. And usually before i draw the hair i like to decide where the ear should be. Then we can decide where the hairline and overall hairshape should be placed.
About the hair shape especially in the back you can add the volume towards the back by drawing some kind of curve line.
Additional tips, you can slightly lift the head tilt so the eye direction look to the front like i draw in the right side.
dire lodge