For hair, I usually, start of with the base shape of the head and treat the hair as they were like ribbons that attach to it. I feel like simplify hair like this at first makes it easier to figure out the shape and direction that the hair goes.
Then I add some lines to show the direction of the hair. I put them mostly where the hair comes out of the head and at the tips too.
And after that it's just a question of detailing as much as you need. You can split the larger ribbons of hair into smaller ones and then add highlights following the direction of the hair.
But overall , I think you have a good base already. You've simplify the hair shape, so all you would need now is to start adding the details.
I hope this was helpful 
