Girls typically part their hair on whichever side is most comfortable for them. This is a highly personal choice and it varies greatly from person to person.
Girls can part their hair either directly down the middle, from the far left or far right, diagonally right or left or zigzag down the center.
To part hair, a girl only needs a brush, a comb and a mirror. After brushing out her hair, a girl must "trace" the line she wants down the crown of her head, split the hair into a right side and left and once again brush the hair out.