how to do this perfect hair?

[system]

Hello, I am trying to do this hair

http://www.allure.com/beauty-trends/blogs/daily-beauty-reporter/2012/08/is-it-boring-to-have-perfect-hair.html

But I am having problems because the hairs are not perfectly under each other. I made different polygroups to have a bit of order, and grooming down to top, but it is very hard to have that perfect result. Any tips?

Thanks