When drawing anime the hair you need to first do the outline of the face, this will be on the "Details of the Face page". The hair is very detailed and can, at times, be very thin. When making hair you should alway suse a mechanicle or a sharp pencil. You should also use different colors so that it isn't just one solid color.
https://orig00.deviantart.net/1c0e/f/2014/032/e/1/au_rivaille_x_reader__starbucks__special__by_flashtide-d74nmen.jpg CC-BY
You'll have to start with what way you want the hair to go. Then you'll want to draw more detailed lines to give it more of a realistic look. Then erase unnecessary lines. After you can make darker lines and curves. There many ways of doing the hair so be creative. Their are many styles you can do.
https://img00.deviantart.net/1676/i/2015/184/c/5/k_on_anime___japan_school_name_by_princesshetalia-d8zr93w.jpg princesshetalia - DeviantArt CC-BY
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