An update of my older tutorial. Men's hair is really just short hair and the styles can be used for female dolls just as male dolls can have all the same hairstyles that female dolls can, but here are some generic male hairstyles all the same.
Base by Silindor
First we need a hairline. This is a technique I learnt from Dea Pixel Junk but as that website is long gone I've done my own version. Draw an I from the mouth up to the middle of the eyes, move it up so the bottom of the I is level with the eyebrows and the top is where the hairline should be. Of course, as doll heads are often cartoony this might not work quite right, so shifty the hairline up and down as needed for your base.
Pick a hairstyle...
The "Spiky"
(Also known (by me) as the "Too Much Hairgel")
The "Flop"
(Also known as the "Boyband")
The "Good Boy"
(Also known as the "Accountant")
The "Tousled"
(Also known as the "Harry Potter")